Search results
Search for "aluminium" in Full Text gives 171 result(s) in Beilstein Journal of Organic Chemistry.
Interaction of a pyrene derivative with cationic [60]fullerene in phospholipid membranes and its effects on photodynamic actions
- Hayato Takagi,
- Çetin Çelik,
- Ryosuke Fukuda,
- Qi Guo,
- Tomohiro Higashino,
- Hiroshi Imahori,
- Yoko Yamakoshi and
- Tatsuya Murakami
Beilstein J. Org. Chem. 2024, 20, 2732–2738, doi:10.3762/bjoc.20.231
- (LUMITRONIX LED-Technik GmbH, Hechingen, Germany) containing 120 LED lamps assembled in an aluminium cylindrical container with a diameter of 8.5 cm. ESR measurements conditions: microwave frequency 9.78 GHz, microwave power 10 mW, receiver gain 5.02 × 104, modulation amplitude 1.00 G, modulation frequency
Graphical Abstract
Figure 1: (a) Chemical structure and schematic illustration of the charge-separated state of a triad molecule...
Figure 2: Differential scanning calorimetry analysis for the phase transition of liposomes (1 mM phospholipid...
Figure 3: UV–vis absorption spectra of liposomes (1 mM phospholipid) with C60 (a) or a cationic derivative of...
Figure 4: Fluorescence spectra of 1-pyrenebutyric acid (PyBA) in cationic derivative of C60 (catC60)-loaded l...
Figure 5: Photoinduced generation of reactive oxygen species (ROS) by cationic derivative of C60 (catC60)-loa...
Novel truxene-based dipyrromethanes (DPMs): synthesis, spectroscopic characterization and photophysical properties
- Shakeel Alvi and
- Rashid Ali
Beilstein J. Org. Chem. 2024, 20, 2163–2170, doi:10.3762/bjoc.20.186
- derivatives (12, 15, and 17) in controlled manner (with appropriate equivalents of acetyl chloride and aluminium chloride) using one-to-threefold Friedel–Crafts acylation reaction(s) at 0 °C to rt in dichloromethane (DCM) solvent (Scheme 1 and Scheme 2). Subsequent condensation of thus prepared acetylated
- . Analytical thin-layer chromatography (TLC) was performed on aluminium plates coated with silica gel by using a suitable mixture of EtOAc and petroleum ether for development purpose. Column chromatography was performed by using silica gel (100–200 mesh) with an appropriate mixture of EtOAc and petroleum ether
Graphical Abstract
Figure 1: Structures of some reported mono-, di- and tri-dipyrromethane derivatives [44-49].
Scheme 1: Synthesis of the mono-DPM-based truxene derivative 14.
Scheme 2: Synthesis of di- and tri-DPM-based truxene derivatives 16 and 18.
Figure 2: UV–vis absorption (left) and fluorescence spectra (right) recorded in chloroform.
Figure 3: Time-resolved fluorescence lifetime.
Light on the sustainable preparation of aryl-cored dibromides
- Fabrizio Roncaglia,
- Alberto Ughetti,
- Nicola Porcelli,
- Biagio Anderlini,
- Andrea Severini and
- Luca Rigamonti
Beilstein J. Org. Chem. 2024, 20, 1076–1087, doi:10.3762/bjoc.20.95
- ), H2SO4 (96 wt %, 3.00 g, 30 mmol, 2.5 equiv), I2 (0.04 g, 0.16 mmol, 0.01 equiv), and CH2Cl2 (1.50 mL) were inserted. The flask, kept under stirring at room temperature (rt), was light-shielded with aluminium foil and a water-cooled condenser was installed on its top. A solution of NaBr (2.88 g, 28 mmol
- mmol, 1.0 equiv), H2SO4 (96 wt %, 3.00 g, 30 mmol, 2.5 equiv), I2 (0.04 g, 0.16 mmol, 0.01 equiv), and chlorobenzene (8.0 mL) were inserted at rt. The flask was shielded from light by means of an aluminium foil and a water-cooled condenser was installed on its top. Once the stirring was started, a
Graphical Abstract
Figure 1: Comparison between the light-initiated radical halogenation of toluene (right), and the Ar-SE bromi...
Figure 2: Toluene halogenation mediated by NBS in absence (left) or exposed to light (right).
Figure 3: Scifinder® reaction hits for the structure “as drawn” (January 2024).
Figure 4: Yields obtained in the preparation of aryl-cored halides.
Skeletal rearrangement of 6,8-dioxabicyclo[3.2.1]octan-4-ols promoted by thionyl chloride or Appel conditions
- Martyn Jevric,
- Julian Klepp,
- Johannes Puschnig,
- Oscar Lamb,
- Christopher J. Sumby and
- Ben W. Greatrex
Beilstein J. Org. Chem. 2024, 20, 823–829, doi:10.3762/bjoc.20.74
- useful in future studies, they were not examined in this work. To investigate the potential uses for the rearrangement products, a series of reactions on the chloroalkyl ethers 11a and 12a was performed (Scheme 5). The reaction of 11a with allyltrimethylsilane catalysed by aluminium chloride resulted in
- the displacement of the chloro substituent with the allyl group, affording 21 in good yield. Electrophilic aromatic substitution reactions at the chloroalkyl ether site were possible when promoted by aluminium chloride, with anisole and diphenyl ether giving addition products 22 and 23 containing
Graphical Abstract
Figure 1: Previous work on migration reactions in 6,8-dioxabicyclooctan-4-ols [18].
Scheme 1: Structures for 10a–c, preparation of 10d–f, and X-ray structure of 10e.
Scheme 2: Rearrangement reactions for 10a–f promoted by SOCl2.
Scheme 3: Reactions of allylic alcohols 15 and 18 with SOCl2.
Scheme 4: Appel reactions of dioxabicyclo[3.2.1]octan-4-ols 10a,e,f and 15.
Scheme 5: Some transformations for the skeletal rearrangement products 11a and 12a and X-ray structure for 24....
Figure 2: Mechanism for the rearrangement of 10, and Newman projection and the X-ray structure of 10d project...
Active-metal template clipping synthesis of novel [2]rotaxanes
- Cătălin C. Anghel,
- Teodor A. Cucuiet,
- Niculina D. Hădade and
- Ion Grosu
Beilstein J. Org. Chem. 2023, 19, 1776–1784, doi:10.3762/bjoc.19.130
- experimental data Commercially available reagents were used without further purification. Compounds 1 [43][47], 4 [48], 9 [49], 10 [44] and M2 [44] were synthesized according to procedures reported in the literature. Thin-layer chromatography (TLC) was performed on silica gel 60 coated aluminium F254 plates
Graphical Abstract
Figure 1: a. Active-metal template (reported in the literature) and b. active-metal template clipping (used i...
Figure 2: Macrocyclic components of the [2]rotaxanes.
Scheme 1: Synthesis of the key intermediates 6 and 8 and of the reference macrocycle M1.
Scheme 2: Synthesis of [2]rotaxanes R1 and R2.
Figure 3: Top: HRESI(+)-MS spectrum of the rotaxane R1 (left) and R2 (right) [experimental (top) and calculat...
Lewis acid-promoted direct synthesis of isoxazole derivatives
- Dengxu Qiu,
- Chenhui Jiang,
- Pan Gao and
- Yu Yuan
Beilstein J. Org. Chem. 2023, 19, 1562–1567, doi:10.3762/bjoc.19.113
- holds significant potential due to their cost-effectiveness as compared to heavy metals. This renders them highly valuable for various applications in the field. Herein, we successfully developed a method that uses sodium nitrite as the source of nitrile oxide, and only applies aluminium trichloride as
Graphical Abstract
Figure 1: Natural products and drug molecules containing isoxazole moieties.
Scheme 1: Traditional methods for the synthesis of isoxazoles and the current approach.
Scheme 2: Reaction scope of alkynes. Conditions: 1 (0.1 mmol, 1 equiv), 2a (0.2 mmol, 2 equiv), AlCl3 (0.3 mm...
Figure 2: Crystal structure of 3i.
Scheme 3: Reaction substrate scope of quinolines. Conditions: 1a (0.1 mmol, 1 equiv), 2 (0.2 mmol, 2 equiv), ...
Scheme 4: Gram scale reaction.
Scheme 5: Control experiments and possible reaction mechanism.
Synthesis of ether lipids: natural compounds and analogues
- Marco Antônio G. B. Gomes,
- Alicia Bauduin,
- Chloé Le Roux,
- Romain Fouinneteau,
- Wilfried Berthe,
- Mathieu Berchel,
- Hélène Couthon and
- Paul-Alain Jaffrès
Beilstein J. Org. Chem. 2023, 19, 1299–1369, doi:10.3762/bjoc.19.96
- presence of dimethylaminopyridine (DMAP). Then, 27.2 reacted with potassium thioacetate to produce the thioester 27.3. Its reduction with lithium aluminium hydride produced the free thiol 27.4 that was used as nucleophile on octadecyl iodide to install the C18 lipid chain. The deprotection of the primary
- Markowska et al. in 1993 [134]. As detailed in Figure 28, the synthesis starts with a Mitsunobu esterification of 28.1 with thioacetic acid to produce the thioester 28.2. Then, the reduction with lithium aluminium hydride produced the thiol 28.3. Finally, the phosphocholine moiety was introduced by using
Graphical Abstract
Figure 1: Chemical structure of some natural ether lipids (ELs).
Figure 2: Synthesis of lyso-PAF and PAF from 1-O-alkylglycerol [64].
Figure 3: Synthesis of lyso-PAF from 1,3-benzylideneglycerol 3.1 [69].
Figure 4: A) Synthesis of the two enantiomers of octadecylglycerol (4.6 and 4.10) from ᴅ-mannitol (4.1); B) s...
Figure 5: Four-step synthesis of PAF 5.6 from (S)-glycidol [73].
Figure 6: Synthesis of 1-O-alkylglycerol A) from solketal, B) from ᴅ- or ʟ-tartaric acid and the intermediate ...
Figure 7: Synthesis of EL building blocks starting from substituted glycidol 7.1a–c [82].
Figure 8: Synthesis of PAF 8.5 by using phosphoramidite 8.2 [86].
Figure 9: Synthesis of oleyl-PAF 9.7 from ʟ-serine [88].
Figure 10: Synthesis of racemic analogues of lyso-PAF 10.8 and PAF 10.9 featuring a phenyl group between the g...
Figure 11: Synthesis of racemic deoxy-lyso-PAF 11.7 and deoxy-PAF 11.8 [91].
Figure 12: Synthesis of racemic thio-PAF 12.8 [93].
Figure 13: Racemic synthesis of 13.6 to illustrate the modification of the glycerol backbone by adding a methy...
Figure 14: Racemic synthesis of 14.5 as an illustration of the introduction of methyl substituents on the glyc...
Figure 15: Synthesis of functionalized sn-2-acyl chains of PC-EL; A) Steglich esterification or acylation reac...
Figure 16: Synthesis of racemic mc-PAF (16.3), a carbamate analogue of PAF [102].
Figure 17: A) Synthesis of (R)-17.2 and (S)-17.6 starting from (S)-solketal (17.1); B) synthesis of N3-PAF (17...
Figure 18: Modification of the phosphocholine polar head to produce PAF analogues [81].
Figure 19: Racemic PAF analogues 19.3 and 19.5 characterized by the absence of the phosphate group [107].
Figure 20: Synthesis of PIP3-PAF (20.7) [108].
Figure 21: Large-scale synthesis of C18-edelfosine (21.8) [116].
Figure 22: Synthesis of C16-edelfosine (22.10) starting from isopropylidene-ʟ-glyceric acid methyl ester (22.1...
Figure 23: Phosphocholine moiety installation by the use of chlorophosphite 23.2 as key reagent [119].
Figure 24: Synthesis of rac-1-alkyl-2-O-methylglycerol (AMG) [120].
Figure 25: Synthesis of stereocontrolled 1-alkyl-2-O-methyl glycerol 25.9 (AMG) from dimethyl ᴅ-tartrate [81].
Figure 26: A) Racemic synthesis of thioether 26.4 [129,130], B) structure of sulfone analogue 26.5 [129].
Figure 27: Stereocontrolled synthesis of C18-edelfosine thioether analogue 27.8 [118].
Figure 28: Synthesis of thioether 28.4 that include a thiophosphate function [134].
Figure 29: Synthesis of ammonium thioether 29.4 and 29.6 [135].
Figure 30: Synthesis of the N-methylamino analogue of edelfosine 30.6 (BN52211) [138].
Figure 31: Synthesis of 1-desoxy analogues of edelfosine; A) with a saturated alkyl chain; B) synthesis of the...
Figure 32: Stereocontrolled synthesis of edelfosine analogue (S)-32.8 featuring a C18:1 lipid chain [142].
Figure 33: Synthesis of edelfosine analogues with modulation of the lipid chain; A) illustration with the synt...
Figure 34: Synthesis of phospholipid featuring a carbamate function to link the lipid chain to the glycerol un...
Figure 35: Synthesis of sesquiterpene conjugates of phospho glycero ether lipids [148].
Figure 36: Racemic synthesis of methyl-substituted glycerol analogues 36.7 and 36.10: A) synthesis of diether ...
Figure 37: Racemic synthesis of ilmofosine (37.6) [155,156].
Figure 38: A) Stereoselective synthesis of 38.5 via a stereoselective hydroboration reaction; B) synthesis of ...
Figure 39: Racemic synthesis of SRI62-834 (39.6) featuring a spiro-tetrahydrofurane heterocycle in position 2 ...
Figure 40: Racemic synthesis of edelfosine analogue 40.5 featuring an imidazole moiety in sn-2 position [160].
Figure 41: Racemic synthesis of fluorine-functionalized EL: A) Synthesis of 41.6 and B) synthesis of 41.8 [161-163].
Figure 42: A) Synthesis of the β-keto-ester 42.6 that also features a decyl linker between the phosphate and t...
Figure 43: Synthesis of phosphonate-based ether lipids; A) edelfosine phosphonate analogue 43.7 and B) thioeth...
Figure 44: Enantioselective synthesis of phosphonates 44.3 and 44.4 [171].
Figure 45: Racemic synthesis of phosphinate-based ether lipid 45.10 [172].
Figure 46: Racemic synthesis of edelfosine arsonium analogue 46.5 [173].
Figure 47: Synthesis of edelfosine dimethylammonium analogue 47.2 [118].
Figure 48: Synthesis of rac-C18-edelfosine methylammonium analogue 48.4 [176].
Figure 49: A) Synthesis of edelfosine N-methylpyrrolidinium analogue 49.2 or N-methylmorpholinium analogue 49.3...
Figure 50: A) Synthesis of edelfosine’s analogue 50.4 with a PE polar group; B) illustration of a pyridinium d...
Figure 51: A) Synthesis of 51.4 featuring a thiazolium cationic moiety; B) synthesis of thiazolium-based EL 51...
Figure 52: Synthesis of cationic ether lipids 52.3, 52.4 and 52.6 [135,183].
Figure 53: Synthesis of cationic carbamate ether lipid 53.5 [184].
Figure 54: Synthesis of cationic sulfonamide 54.5 [185].
Figure 55: Chemical structure of ONO-6240 (55.1) and SRI-63-119 (55.2).
Figure 56: Synthesis of non-ionic ether lipids 56.2–56.9 [188].
Figure 57: Synthesis of ether lipid conjugated to foscarnet 57.6 [189].
Figure 58: A) Synthesis of ether lipid conjugated to arabinofuranosylcytosine; B) synthesis of AZT conjugated ...
Figure 59: Synthesis of quercetin conjugate to edelfosine [191].
Figure 60: Synthesis of 60.8 (Glc-PAF) [194].
Figure 61: A) Synthesis of amino ether lipid 61.7 functionalized with a rhamnose unit and its amide analogue 6...
Figure 62: A) Synthesis of glucose ether lipid 62.4; B) structure of ether lipid 62.5 possessing a maltose uni...
Figure 63: A) Synthesis of glucuronic methyl ester 63.8; B) structure of cellobiose 63.9 and maltose 63.10 ana...
Figure 64: A) Synthesis of maltosyl glycerolipid 64.7; B) structure of lactose analogue 64.8 prepared followin...
Figure 65: A) Asymmetric synthesis of the aglycone moiety starting from allyl 4-methoxyphenyl ether; B) glycos...
Figure 66: A) Synthesis of ohmline possessing a lactose moiety. B) Structure of other glyco glycero lipids pre...
Figure 67: A) Synthesis of lactose-glycerol ether lipid 67.5; B) analogues possessing a maltose (67.6) or meli...
Figure 68: Synthesis of digalactosyl EL 68.6, A) by using trityl, benzyl and acetyl protecting groups, B) by u...
Figure 69: A) Synthesis of α-ohmline; B) structure of disaccharide ether lipids prepared by using similar meth...
Figure 70: Synthesis of lactose ether lipid 70.3 and its analogue 70.6 featuring a carbamate function as linke...
Figure 71: Synthesis of rhamnopyranoside diether 71.4 [196].
Figure 72: Synthesis of 1-O-hexadecyl-2-O-methyl-3-S-(α-ᴅ-1'-thioglucopyranosyl)-sn-glycerol (72.5) [225].
Figure 73: A) Preparation of lipid intermediate 73.4; B) synthesis of 2-desoxy-C-glycoside 73.10 [226].
Figure 74: Synthesis of galactose-pyridinium salt 74.3 [228].
Figure 75: Synthesis of myo-inositol derivative Ino-C2-PAF (75.10) [230].
Figure 76: A) Synthesis of myo-inositol phosphate building block 76.7; B) synthesis of myo-inositolphosphate d...
Figure 77: A) Synthesis of phosphatidyl-3-desoxy-inositol 77.4; B) synthesis of phosphono-3-desoxyinositol 77.9...
Figure 78: A) Structure of diether phosphatidyl-myo-inositol-3,4-diphosphate 78.1; B) synthesis of phosphatidy...
Figure 79: A) Synthesis of diether-phosphatidyl derivative 79.4 featuring a hydroxymethyl group in place of a ...
Figure 80: Synthesis of Glc-amine-PAF [78].
Figure 81: Synthesis of glucosamine ether lipid 81.4 and its analogues functionalized in position 3 of the ami...
Figure 82: Synthesis of fully deprotected aminoglucoside ether lipid 82.5 [246].
Figure 83: Synthesis of C-aminoglycoside 83.12 using Ramberg–Bäcklund rearrangement as a key step [250].
Figure 84: A) List of the most important glyco lipids and amino glyco lipids included in the study of Arthur a...
Figure 85: Synthesis of mannosamine ether lipid 85.6 [254].
Figure 86: A) Synthesis of glucosamine ether lipids with a non-natural ʟ-glucosamine moiety; B) synthesis of e...
Figure 87: A) Structure of the most efficient anticancer agents 87.1–87.4 featuring a diamino glyco ether lipi...
Figure 88: A) Synthesis of diamino glyco ether lipid 87.4; B) synthesis of bis-glycosylated ether lipid 88.10 [256]....
Figure 89: Synthesis of triamino ether lipid 89.4 [260].
Figure 90: Synthesis of chlorambucil conjugate 90.7 [261].
Figure 91: Three main methods for the preparation of glycerol ether lipid 91.3; A) from solketal and via a tri...
Figure 92: Four different methods for the installation of the phosphocholine polar head group; A) method using...
Figure 93: Illustration of two methods for the installation of saccharides or aminosaccharides; A) O-glycosyla...
Unravelling a trichloroacetic acid-catalyzed cascade access to benzo[f]chromeno[2,3-h]quinoxalinoporphyrins
- Chandra Sekhar Tekuri,
- Pargat Singh and
- Mahendra Nath
Beilstein J. Org. Chem. 2023, 19, 1216–1224, doi:10.3762/bjoc.19.89
- received unless otherwise stated. The column chromatographic purifications of all products were carried out using either activated neutral aluminium oxide (Brokmann grade I-II, Merck). The melting points of all newly prepared products were determined on a Büchi M-560 melting point apparatus. 1H NMR (400
- on silica gel 60 F254 (pre-coated aluminium) sheets from Merck. General procedure for the synthesis of copper(II) benzo[f]chromeno[2,3-h]quinoxalinoporphyrins 3–8 To a solution of copper(II) 2,3-diamino-meso-tetraarylporphyrin (1; 0.131 mmol) in chloroform (20 mL), 2-hydroxynaphthalene-1,4-dione (2
Graphical Abstract
Scheme 1: Synthesis of benzo[f]chromeno[2,3-h]quinoxalinoporphyrins 3–16.
Figure 1: Plausible mechanism for the formation of copper(II) benzo[f]chromeno[2,3-h]quinoxalinoporphyrins.
Scheme 2: Sequential synthesis of copper(II) benzo[f]chromeno[2,3-h]quinoxalinoporphyrin 3.
Figure 2: Electronic absorption spectra of copper(II) benzo[f]chromeno[2,3-h]quinoxalinoporphyrins 3–8 in CHCl...
Figure 3: Electronic absorption spectra of free-base benzo[f]chromeno[2,3-h]quinoxalinoporphyrins 9–13 in CHCl...
Figure 4: Electronic absorption spectra of zinc(II) benzo[f]chromeno[2,3-h]quinoxalinoporphyrins 14–16 in CHCl...
Figure 5: (a) Emission spectra of free-base benzo[f]chromeno[2,3-h]quinoxalinoporphyrins 9–13 and (b) emissio...
CO2 complexation with cyclodextrins
- Cecilie Høgfeldt Jessen,
- Jesper Bendix,
- Theis Brock Nannestad,
- Heloisa Bordallo,
- Martin Jæger Pedersen,
- Christian Marcus Pedersen and
- Mikael Bols
Beilstein J. Org. Chem. 2023, 19, 1021–1027, doi:10.3762/bjoc.19.78
- [20]. In the reported structure, CO2 was refined with an occupancy of 0.84. TGA measurements. These analyses were carried out on a Netzsch TG 209 F1 Libra fitted with a FTIR detector from Bruker. Samples were prepared by crushing the crystals before putting them in an aluminium crucible ensuring full
Graphical Abstract
Figure 1: Structure of cyclodextrins 1–6 studied in this work.
Figure 2: X-ray crystal structure of CO2 bound to α-CD.
Figure 3: TGA curve (blue) and dTGA curve (red) for CO2-1 crystals. Two lumps are seen with the former predom...
Figure 4: Cell used to measure vis spectra under pressure (left), structure of 7 (middle) and spectrum of 7 (...
Figure 5: Binding of CO2 to 1 as a function of pressure.
Group 13 exchange and transborylation in catalysis
- Dominic R. Willcox and
- Stephen P. Thomas
Beilstein J. Org. Chem. 2023, 19, 325–348, doi:10.3762/bjoc.19.28
- by σ-bond metathesis, a redox neutral process (Scheme 1). Stoichiometric group 13 exchange reactions are key to the synthesis of group 13 reagents including in organoboron chemistry [11][12][13][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28], and more recently with aluminium [29][30][31
- give formal hydrofunctionalisation products (Scheme 18) [80][81][82][83]. Although no mechanism was proposed, a rare B‒C/Al‒H exchange may be responsible for catalytic turnover. Aluminium catalysis The aluminium-catalysed hydroboration of alkynes with HBpin has been well studied with a variety of
- aluminium complexes having been shown to be catalytically active (Scheme 19a) [84][85][86][87][88][89][90][91][92][93]. Roesky reported the first example, using an N,N′-bis-2,6-diisopropylphenyl diketiminate (NacNac)-supported aluminium dihydride complex as the catalyst [84]. Through computational analysis
Graphical Abstract
Scheme 1: Group 13 exchange.
Scheme 2: Borane-catalysed hydroboration of alkynes and the proposed mechanism.
Scheme 3: a) Borane-catalysed hydroboration of alkenes and the proposed mechanism. b) H-B-9-BBN-catalysed dou...
Scheme 4: a) Amine-borane-catalysed C‒H borylation of heterocycles and the proposed mechanism. b) Benzoic aci...
Scheme 5: Bis(pentafluorophenyl)borane-catalysed dimerisation of allenes and the proposed mechanism.
Scheme 6: Alkoxide-promoted hydroboration of heterocycles and the proposed mechanism.
Scheme 7: Borane-catalysed reduction of indoles and the proposed mechanism.
Scheme 8: H-B-9-BBN-catalysed hydrocyanation of enones and the proposed mechanism.
Scheme 9: Borane-catalysed hydroboration of nitriles and the proposed mechanism.
Scheme 10: Myrtanylborane-catalysed asymmetric reduction of propargylic ketones and the proposed mechanism.
Scheme 11: H-B-9-BBN-catalysed C–F esterification of alkyl fluorides and the proposed mechanism.
Scheme 12: H-B-9-BBN-catalysed 1,4-hydroboration of enones and the proposed mechanism.
Scheme 13: Boric acid-promoted reduction of esters, lactones, and carbonates and the proposed mechanism.
Scheme 14: H-B-9-BBN-catalysed reductive aldol-type reaction and the proposed mechanism.
Scheme 15: H-B-9-BBN-catalysed diastereoselective allylation of ketones and the Ph-BBD-catalysed enantioselect...
Scheme 16: H-B-9-BBN-catalysed C–F arylation of benzyl fluorides and the proposed mechanism.
Scheme 17: Borane-catalysed S‒H borylation of thiols and the proposed mechanism.
Scheme 18: Borane-catalysed hydroalumination of alkenes and allenes.
Scheme 19: a) Aluminium-catalysed hydroboration of alkynes and example catalysts. b) Deprotonation mechanistic...
Scheme 20: Aluminium-catalysed hydroboration of alkenes and the proposed mechanism.
Scheme 21: Aluminium-catalysed C–H borylation of terminal alkynes and the proposed mechanism.
Scheme 22: Aluminium-catalysed dehydrocoupling of amines, alcohols, and thiols with H-B-9-BBN or HBpin and the...
Scheme 23: Aluminium-catalysed hydroboration of unsaturated compounds and the general reaction mechanism.
Scheme 24: a) Gallium-catalysed asymmetric hydroboration of ketones and the proposed mechanism. b) Gallium-cat...
Scheme 25: Gallium(I)-catalysed allylation/propargylation of acetals and aminals and the proposed mechanism.
Scheme 26: Indium(I)-catalysed allylation/propargylation of acetals, aminals, and alkyl ethers.
Scheme 27: Iron–indium cocatalysed double hydroboration of nitriles and the proposed mechanism.
Figure 1: a) The number of reports for a given group 13 exchange in catalysis. b) Average free energy barrier...
Inclusion complexes of the steroid hormones 17β-estradiol and progesterone with β- and γ-cyclodextrin hosts: syntheses, X-ray structures, thermal analyses and API solubility enhancements
- Alexios I. Vicatos,
- Zakiena Hoossen and
- Mino R. Caira
Beilstein J. Org. Chem. 2022, 18, 1749–1762, doi:10.3762/bjoc.18.184
- with TRIOS software [50]. Sample preparation entailed drying the crystal surfaces from the mother liquor and placing the crystals in a crimped aluminium pan with two venting holes. A constant rate of 10 K·min−1 was used to heat the samples (mass range 1–2 mg) under dry N2 purge gas with a flux of 60
Graphical Abstract
Figure 1: Chemical structures of 17β-estradiol (top) and progesterone (bottom).
Figure 2: The PXRD patterns of the β-CD·PRO complex produced via kneading (2:1), an isostructural β-CD comple...
Figure 3: The PXRD patterns of the γ-CD·PRO complex produced via kneading (3:2), an isostructural γ-CD comple...
Figure 4: (a) The crystal morphology of β-CD·BES recorded with polarised light. (b) The crystal morphology of...
Figure 5: (a) A representative DSC curve (n = 2) of β-CD·BES, with the respective TGA curve (n = 3); (b) a re...
Figure 6: Stereoscopic views of the host molecule and water oxygen atoms in the ASUs of (a) β-CD·BES and (b) ...
Figure 7: A stereoscopic view down the c-axis displaying the packing arrangement for β-CD·BES.
Figure 8: A stereoscopic view down the c-axis displaying the packing arrangement for β-CD·PRO.
Figure 9: A stereoscopic view of the host atoms and water oxygen atoms in the ASU of γ-CD·PRO.
Figure 10: The host atoms and water oxygen atoms of the ASU viewed down the c-axis, showing that the water mol...
Figure 11: The distinct packing arrangement of the repeat unit of the host molecules in γ-CD·PRO. The four-fol...
Figure 12: A stereoscopic view of γ-CD·PRO viewed down the c-axis, which displays the infinite channel packing...
Synthesis of the biologically important dideuterium-labelled adenosine triphosphate analogue ApppI(d2)
- Petri A. Turhanen
Beilstein J. Org. Chem. 2022, 18, 1466–1470, doi:10.3762/bjoc.18.153
- -enoic acid (2) was then reduced to 3-methylbut-3-en-1,1-d2-1-ol (3) with lithium aluminium deuteride, followed by tosylation with tosyl chloride. Tosylated 3-methylbut-3-en-1,1-d2-1-ol 4 was then treated with ATP TBA salt in acetonitrile at 45 °C for 55 h to give the target product ApppI(d2) (Scheme 1
Graphical Abstract
Figure 1: Structure of natural pyrophosphate and examples of NBPs (Z = Na or H).
Figure 2: Structures of ATP analogues ApppI and ApppD (Z = Na or H).
Scheme 1: Synthetic route to target compound ApppI(d2) (Z = TBA).
First example of organocatalysis by cathodic N-heterocyclic carbene generation and accumulation using a divided electrochemical flow cell
- Daniele Rocco,
- Ana A. Folgueiras-Amador,
- Richard C. D. Brown and
- Marta Feroci
Beilstein J. Org. Chem. 2022, 18, 979–990, doi:10.3762/bjoc.18.98
- Sigma-Aldrich and Alfa Aesar and used as received. All air/moisture sensitive reactions were carried out under an inert atmosphere, in oven-dried or flame-dried glassware. TLC was performed on aluminium plates precoated with silica gel 60 with an F254 indicator; visualized under UV light (254 nm) and/or
- electrochemical reactor. C/PVDF anode before (A) and after (B) the first experiment (Table 1, entry 1). Expanded view of the electrochemical cell components: (a) Aluminium end plates; (b) insulating PTFE foil, (c) copper plate for electrical contact; (d) carbon electrode; (e) PTFE gasket (reaction channel and
Graphical Abstract
Scheme 1: Electrochemical generation of NHC.
Scheme 2: Transformation of electrochemically generated NHC into the corresponding thione by its reaction wit...
Scheme 3: Umpolung of the aldehyde carbonyl carbon atom. Formation of the Breslow intermediate using NHCs.
Figure 1: Schematic representation of a plane-parallel plate flow electrochemical reactor.
Figure 2: C/PVDF anode before (A) and after (B) the first experiment (Table 1, entry 1).
Scheme 4: Electrogenerated NHC-catalyzed self-annulation of cinnamaldehyde.
Scheme 5: Byproduct obtained from the reaction between methanol and the Breslow intermediate.
Figure 3: Expanded view of the electrochemical cell components: (a) Aluminium end plates; (b) insulating PTFE...
Introducing a new 7-ring fused diindenone-dithieno[3,2-b:2',3'-d]thiophene unit as a promising component for organic semiconductor materials
- Valentin H. K. Fell,
- Joseph Cameron,
- Alexander L. Kanibolotsky,
- Eman J. Hussien and
- Peter J. Skabara
Beilstein J. Org. Chem. 2022, 18, 944–955, doi:10.3762/bjoc.18.94
- which oxalyl chloride was added at room temperature, and then reacted with aluminium trichloride at 0 °C. The resulting material was not soluble in cold dichloromethane/chloroform, but was found to be sufficiently soluble in hot chlorinated solvents. NMR spectroscopy in deuterated DMSO indicated that
- under vacuum. Details of the synthesis are described in Supporting Information File 1. After fresh, anhydrous dichloromethane was added, the mixture was cooled to 0 °C in a water–ice bath, and resublimed aluminium trichloride was added. The mixture was allowed to warm to room temperature, and was then
Graphical Abstract
Figure 1: EtH-T-DI-DTT (1).
Figure 2: Previously published, ‘bent’ diindenodithienothiophenes [16,24,25].
Figure 3: With crystalline films of 2,7-dioctyl[1]benzothieno[3,2-b][1]-benzothiophene (8), obtained by off-c...
Figure 4: ITIC, a system with fused thiophenes, in combination with donor polymer 11, also featuring a fused ...
Figure 5: The fluorinated derivative of ITIC, IT-4F, achieved, with donor polymer 13, PCEs in OPVs up to 17% [8]....
Figure 6: The non-fullerene acceptor Y6 (14) [30], in combination with donor polymer 15, both fused thiophene sys...
Figure 7: With a three component system of PBQx-TF, eC9-2Cl, and F-BTA3, a PCE of 19% was achieved [32].
Scheme 1: Synthetic route from thiophene to 2,6-bis(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)dithieno[3,2-b...
Scheme 2: Ring closure of key intermediate 27 to achieve 29: a) Methyl 5-bromo-2-iodobenzoate, Aliquat 336®, ...
Scheme 3: Synthesis of thiophene derivative 32: a) Magnesium, 2-ethylhexylbromide, spatula tip iodine, anhydr...
Scheme 4: Synthesis of the soluble target structure EtH-T-DI-DTT (1): a) 32, Pd(PPh3)4, K2CO3, THF, H2O, 70 °...
Figure 8: Normalised UV–vis spectra of EtH-T-DI-DTT in 10−5 M CH2Cl2 solution and in the solid state.
Figure 9: Cyclic voltammogram for EtH-T-DI-DTT (1), at a scan rate of 0.1 V s−1 using a Pt disk as the workin...
Figure 10: The structure of EtH-T-DI-DTT optimised on the B3LYP/6-311g(d,p) level of theory, viewed from the (...
Facile and innovative catalytic protocol for intramolecular Friedel–Crafts cyclization of Morita–Baylis–Hillman adducts: Synergistic combination of chiral (salen)chromium(III)/BF3·OEt2 catalysis
- Karthikeyan Soundararajan,
- Helen Ratna Monica Jeyarajan,
- Raju Subimol Kamarajapurathu and
- Karthik Krishna Kumar Ayyanoth
Beilstein J. Org. Chem. 2021, 17, 2186–2193, doi:10.3762/bjoc.17.140
- convinced us to explore them as suitable chiral Lewis acid catalysts for the Friedel–Crafts cyclization of MBH adducts. Mononuclear(salen) complexes of aluminium, chromium, manganese and cobalt were chosen and screened for the current investigation. Results and Discussion To evaluate the scope of the
Graphical Abstract
Scheme 1: Literature-reported approaches to synthesise indene from MBH adducts [10-14].
Scheme 2: Proposed model for the intramolecular Friedel–Crafts cyclization.
Scheme 3: Reactions of azomethine imine 7a with 2-substituted 1H-indenes 6a and 6b.
Design, synthesis and photophysical properties of novel star-shaped truxene-based heterocycles utilizing ring-closing metathesis, Clauson–Kaas, Van Leusen and Ullmann-type reactions as key tools
- Shakeel Alvi and
- Rashid Ali
Beilstein J. Org. Chem. 2021, 17, 1374–1384, doi:10.3762/bjoc.17.96
- . Pyrrole was used after distillation. Analytical thin-layer chromatography (TLC) was performed on aluminium plates coated with silica gel by using a suitable mixture of EtOAc and petroleum ether for development. Column chromatography was performed by using silica gel (100–200 mesh) with an appropriate
Graphical Abstract
Scheme 1: Retrosynthetic pathways to the pyrrole-based C3-symmetric truxene derivative 6.
Scheme 2: Synthesis of tripyrrolotruxene 6 via cyclotrimerization and RCM as crucial steps.
Scheme 3: Synthesis of star-shaped molecule 6 utilizing the Clauson–Kaas pyrrole strategy.
Scheme 4: Synthesis of truxene derivative 6 involving Ullmann-type cross-coupling reaction.
Scheme 5: Synthesis of imidazole and benzimidazole containing truxene derivatives 14 and 16.
Scheme 6: Construction of truxene-based di- and trioxazole derivatives 21 and 20.
Scheme 7: Synthesis of benzene-bridged rings containing trioxazolotruxene system 25.
Figure 1: Normalized absorption (left); fluorescence spectra (right) of the synthesized truxene derivatives (...
A comprehensive review of flow chemistry techniques tailored to the flavours and fragrances industries
- Guido Gambacorta,
- James S. Sharley and
- Ian R. Baxendale
Beilstein J. Org. Chem. 2021, 17, 1181–1312, doi:10.3762/bjoc.17.90
Graphical Abstract
Figure 1: Representative shares of the global F&F market (2018) segmented on their applications [1].
Figure 2: General structure of an international fragrance company [2].
Figure 3: The Michael Edwards fragrance wheel.
Figure 4: Examples of oriental (1–3), woody (4–7), fresh (8–10), and floral (11 and 12) notes.
Figure 5: A basic depiction of batch vs flow.
Scheme 1: Examples of reactions for which flow processing outperforms batch.
Scheme 2: Some industrially important aldol-based transformations.
Scheme 3: Biphasic continuous aldol reactions of acetone and various aldehydes.
Scheme 4: Aldol synthesis of 43 in flow using LiHMDS as the base.
Scheme 5: A semi-continuous synthesis of doravirine (49) involving a key aldol reaction.
Scheme 6: Enantioselective aldol reaction using 5-(pyrrolidin-2-yl)tetrazole (51) as catalyst in a microreact...
Scheme 7: Gröger's example of asymmetric aldol reaction in aqueous media.
Figure 6: Immobilised reagent column reactor types.
Scheme 8: Photoinduced thiol–ene coupling preparation of silica-supported 5-(pyrrolidin-2-yl)tetrazole 63 and...
Scheme 9: Continuous-flow approach for enantioselective aldol reactions using the supported catalyst 67.
Scheme 10: Ötvös’ employment of a solid-supported peptide aldol catalyst in flow.
Scheme 11: The use of proline tetrazole packed in a column for aldol reaction between cyclohexanone (65) and 2...
Scheme 12: Schematic diagram of an aminosilane-grafted Si-Zr-Ti/PAI-HF reactor for continuous-flow aldol and n...
Scheme 13: Continuous-flow condensation for the synthesis of the intermediate 76 to nabumetone (77) and Microi...
Scheme 14: Synthesis of ψ-Ionone (80) in continuous-flow via aldol condensation between citral (79) and aceton...
Scheme 15: Synthesis of β-methyl-ionones (83) from citral (79) in flow. The steps are separately described, an...
Scheme 16: Continuous-flow synthesis of 85 from 84 described by Gavriilidis et al.
Scheme 17: Continuous-flow scCO2 apparatus for the synthesis of 2-methylpentanal (87) and the self-condensed u...
Scheme 18: Chen’s two-step flow synthesis of coumarin (90).
Scheme 19: Pechmann condensation for the synthesis of 7-hydroxyxcoumarin (93) in flow. The setup extended to c...
Scheme 20: Synthesis of the dihydrojasmonate 35 exploiting nitro derivative proposed by Ballini et al.
Scheme 21: Silica-supported amines as heterogeneous catalyst for nitroaldol condensation in flow.
Scheme 22: Flow apparatus for the nitroaldol condensation of p-hydroxybenzaldehyde (102) to nitrostyrene 103 a...
Scheme 23: Nitroaldol reaction of 64 to 105 employing a quaternary ammonium functionalised PANF.
Scheme 24: Enantioselective nitroaldol condensation for the synthesis of 108 under flow conditions.
Scheme 25: Enatioselective synthesis of 1,2-aminoalcohol 110 via a copper-catalysed nitroaldol condensation.
Scheme 26: Examples of Knoevenagel condensations applied for fragrance components.
Scheme 27: Flow apparatus for Knoevenagel condensation described in 1989 by Venturello et al.
Scheme 28: Knoevenagel reaction using a coated multichannel membrane microreactor.
Scheme 29: Continuous-flow apparatus for Knoevenagel condensation employing sugar cane bagasse as support deve...
Scheme 30: Knoevenagel reaction for the synthesis of 131–135 in flow using an amine-functionalised silica gel. ...
Scheme 31: Continuous-flow synthesis of compound 137, a key intermediate for the synthesis of pregabalin (138)...
Scheme 32: Continuous solvent-free apparatus applied for the synthesis of compounds 140–143 using a TSE. Throu...
Scheme 33: Lewis et al. developed a spinning disc reactor for Darzens condensation of 144 and a ketone to furn...
Scheme 34: Some key industrial applications of conjugate additions in the F&F industry.
Scheme 35: Continuous-flow synthesis of 4-(2-hydroxyethyl)thiomorpholine 1,1-dioxide (156) via double conjugat...
Scheme 36: Continuous-flow system for Michael addition using CsF on alumina as the catalyst.
Scheme 37: Calcium chloride-catalysed asymmetric Michael addition using an immobilised chiral ligand.
Scheme 38: Continuous multistep synthesis for the preparation of (R)-rolipram (173). Si-NH2: primary amine-fun...
Scheme 39: Continuous-flow Michael addition using ion exchange resin Amberlyst® A26.
Scheme 40: Preparation of the heterogeneous catalyst 181 developed by Paixão et al. exploiting Ugi multicompon...
Scheme 41: Continuous-flow system developed by the Paixão’s group for the preparation of Michael asymmetric ad...
Scheme 42: Continuous-flow synthesis of nitroaldols catalysed by supported catalyst 184 developed by Wennemers...
Scheme 43: Heterogenous polystyrene-supported catalysts developed by Pericàs and co-workers.
Scheme 44: PANF-supported pyrrolidine catalyst for the conjugate addition of cyclohexanone (65) and trans-β-ni...
Scheme 45: Synthesis of (−)-paroxetine precursor 195 developed by Ötvös, Pericàs, and Kappe.
Scheme 46: Continuous-flow approach for the 5-step synthesis of (−)-oseltamivir (201) as devised by Hayashi an...
Scheme 47: Continuous-flow enzyme-catalysed Michael addition.
Scheme 48: Continuous-flow copper-catalysed 1,4 conjugate addition of Grignard reagents to enones. Reprinted w...
Scheme 49: A collection of commonly encountered hydrogenation reactions.
Figure 7: The ThalesNano H-Cube® continuous-flow hydrogenator.
Scheme 50: Chemoselective reduction of an α,β-unsaturated ketone using the H-Cube® reactor.
Scheme 51: Incorporation of Lindlar’s catalyst into the H-Cube® reactor for the reduction of an alkyne.
Scheme 52: Continuous-flow semi-hydrogenation of alkyne 208 to 209 using SACs with H-Cube® system.
Figure 8: The standard setups for tube-in-tube gas–liquid reactor units.
Scheme 53: Homogeneous hydrogenation of olefins using a tube-in-tube reactor setup.
Scheme 54: Recyclable heterogeneous flow hydrogenation system.
Scheme 55: Leadbeater’s reverse tube-in-tube hydrogenation system for olefin reductions.
Scheme 56: a) Hydrogenation using a Pd-immobilised microchannel reactor (MCR) and b) a representation of the i...
Scheme 57: Hydrogenation of alkyne 238 exploiting segmented flow in a Pd-immobilised capillary reactor.
Scheme 58: Continuous hydrogenation system for the preparation of cyrene (241) from (−)-levoglucosenone (240).
Scheme 59: Continuous hydrogenation system based on CSMs developed by Hornung et al.
Scheme 60: Chemoselective reduction of carbonyls (ketones over aldehydes) in flow.
Scheme 61: Continuous system for the semi-hydrogenation of 256 and 258, developed by Galarneau et al.
Scheme 62: Continuous synthesis of biodiesel fuel 261 from lignin-derived furfural acetone (260).
Scheme 63: Continuous synthesis of γ-valerolacetone (263) via CTH developed by Pineda et al.
Scheme 64: Continuous hydrogenation of lignin-derived biomass (products 265, 266, and 267) using a sustainable...
Scheme 65: Ru/C or Rh/C-catalysed hydrogenation of arene in flow as developed by Sajiki et al.
Scheme 66: Polysilane-immobilized Rh–Pt-catalysed hydrogenation of arenes in flow by Kobayashi et al.
Scheme 67: High-pressure in-line mixing of H2 for the asymmetric reduction of 278 at pilot scale with a 73 L p...
Figure 9: Picture of the PFR employed at Eli Lilly & Co. for the continuous hydrogenation of 278 [287]. Reprinted ...
Scheme 68: Continuous-flow asymmetric hydrogenation using Oppolzer's sultam 280 as chiral auxiliary.
Scheme 69: Some examples of industrially important oxidation reactions in the F&F industry. CFL: compact fluor...
Scheme 70: Gold-catalysed heterogeneous oxidation of alcohols in flow.
Scheme 71: Uozumi’s ARP-Pt flow oxidation protocol.
Scheme 72: High-throughput screening of aldehyde oxidation in flow using an in-line GC.
Scheme 73: Permanganate-mediated Nef oxidation of nitroalkanes in flow with the use of in-line sonication to p...
Scheme 74: Continuous-flow aerobic anti-Markovnikov Wacker oxidation.
Scheme 75: Continuous-flow oxidation of 2-benzylpyridine (312) using air as the oxidant.
Scheme 76: Continuous-flow photo-oxygenation of monoterpenes.
Scheme 77: A tubular reactor design for flow photo-oxygenation.
Scheme 78: Glucose oxidase (GOx)-mediated continuous oxidation of glucose using compressed air and the FFMR re...
Scheme 79: Schematic continuous-flow sodium hypochlorite/TEMPO oxidation of alcohols.
Scheme 80: Oxidation using immobilised TEMPO (344) was developed by McQuade et al.
Scheme 81: General protocol for the bleach/catalytic TBAB oxidation of aldehydes and alcohols.
Scheme 82: Continuous-flow PTC-assisted oxidation using hydrogen peroxide. The process was easily scaled up by...
Scheme 83: Continuous-flow epoxidation of cyclohexene (348) and in situ preparation of m-CPBA.
Scheme 84: Continuous-flow epoxidation using DMDO as oxidant.
Scheme 85: Mukayama aerobic epoxidation optimised in flow mode by the Favre-Réguillon group.
Scheme 86: Continuous-flow asymmetric epoxidation of derivatives of 359 exploiting a biomimetic iron catalyst.
Scheme 87: Continuous-flow enzymatic epoxidation of alkenes developed by Watts et al.
Scheme 88: Engineered multichannel microreactor for continuous-flow ozonolysis of 366.
Scheme 89: Continuous-flow synthesis of the vitamin D precursor 368 using multichannel microreactors. MFC: mas...
Scheme 90: Continuous ozonolysis setup used by Kappe et al. for the synthesis of various substrates employing ...
Scheme 91: Continuous-flow apparatus for ozonolysis as developed by Ley et al.
Scheme 92: Continuous-flow ozonolysis for synthesis of vanillin (2) using a film-shear flow reactor.
Scheme 93: Examples of preparative methods for ajoene (386) and allicin (388).
Scheme 94: Continuous-flow oxidation of thioanisole (389) using styrene-based polymer-supported peroxytungstat...
Scheme 95: Continuous oxidation of thiosulfinates using Oxone®-packed reactor.
Scheme 96: Continuous-flow electrochemical oxidation of thioethers.
Scheme 97: Continuous-flow oxidation of 400 to cinnamophenone (235).
Scheme 98: Continuous-flow synthesis of dehydrated material 401 via oxidation of methyl dihydrojasmonate (33).
Scheme 99: Some industrially important transformations involving Grignard reagents.
Scheme 100: Grachev et al. apparatus for continuous preparation of Grignard reagents.
Scheme 101: Example of fluidized Mg bed reactor with NMR spectrometer as on-line monitoring system.
Scheme 102: Continuous-flow synthesis of Grignard reagents and subsequent quenching reaction.
Figure 10: Membrane-based, liquid–liquid separator with integrated pressure control [52]. Adapted with permission ...
Scheme 103: Continuous-flow synthesis of 458, an intermediate to fluconazole (459).
Scheme 104: Continuous-flow synthesis of ketones starting from benzoyl chlorides.
Scheme 105: A Grignard alkylation combining CSTR and PFR technologies with in-line infrared reaction monitoring....
Scheme 106: Continuous-flow preparation of 469 from Grignard addition of methylmagnesium bromide.
Scheme 107: Continuous-flow synthesis of Grignard reagents 471.
Scheme 108: Preparation of the Grignard reagent 471 using CSTR and the continuous process for synthesis of the ...
Scheme 109: Continuous process for carboxylation of Grignard reagents in flow using tube-in-tube technology.
Scheme 110: Continuous synthesis of propargylic alcohols via ethynyl-Grignard reagent.
Scheme 111: Silica-supported catalysed enantioselective arylation of aldehydes using Grignard reagents in flow ...
Scheme 112: Acid-catalysed rearrangement of citral and dehydrolinalool derivatives.
Scheme 113: Continuous stilbene isomerisation with continuous recycling of photoredox catalyst.
Scheme 114: Continuous-flow synthesis of compound 494 as developed by Ley et al.
Scheme 115: Selected industrial applications of DA reaction.
Scheme 116: Multistep flow synthesis of the spirocyclic structure 505 via employing DA cycloaddition.
Scheme 117: Continuous-flow DA reaction developed in a plater flow reactor for the preparation of the adduct 508...
Scheme 118: Continuous-flow DA reaction using a silica-supported imidazolidinone organocatalyst.
Scheme 119: Batch vs flow for the DA reaction of (cyclohexa-1,5-dien-1-yloxy)trimethylsilane (513) with acrylon...
Scheme 120: Continuous-flow DA reaction between 510 and 515 using a shell-core droplet system.
Scheme 121: Continuous-flow synthesis of bicyclic systems from benzyne precursors.
Scheme 122: Continuous-flow synthesis of bicyclic scaffolds 527 and 528 for further development of potential ph...
Scheme 123: Continuous-flow inverse-electron hetero-DA reaction to pyridine derivatives such as 531.
Scheme 124: Comparison between batch and flow for the synthesis of pyrimidinones 532–536 via retro-DA reaction ...
Scheme 125: Continuous-flow coupled with ultrasonic system for preparation of ʟ-ascorbic acid derivatives 539 d...
Scheme 126: Two-step continuous-flow synthesis of triazole 543.
Scheme 127: Continuous-flow preparation of triazoles via CuAAC employing 546-based heterogeneous catalyst.
Scheme 128: Continuous-flow synthesis of compounds 558 through A3-coupling and 560 via AgAAC both employing the...
Scheme 129: Continuous-flow photoinduced [2 + 2] cycloaddition for the preparation of bicyclic derivatives of 5...
Scheme 130: Continuous-flow [2 + 2] and [5 + 2] cycloaddition on large scale employing a flow reactor developed...
Scheme 131: Continuous-flow preparation of the tricyclic structures 573 and 574 starting from pyrrole 570 via [...
Scheme 132: Continuous-flow [2 + 2] photocyclization of cinnamates.
Scheme 133: Continuous-flow preparation of cyclobutane 580 on a 5-plates photoreactor.
Scheme 134: Continuous-flow [2 + 2] photocycloaddition under white LED lamp using heterogeneous PCN as photocat...
Figure 11: Picture of the parallel tube flow reactor (PTFR) "The Firefly" developed by Booker-Milburn et al. a...
Scheme 135: Continuous-flow acid-catalysed [2 + 2] cycloaddition between silyl enol ethers and acrylic esters.
Scheme 136: Continuous synthesis of lactam 602 using glass column reactors.
Scheme 137: In situ generation of ketenes for the Staudinger lactam synthesis developed by Ley and Hafner.
Scheme 138: Application of [2 + 2 + 2] cycloadditions in flow employed by Ley et al.
Scheme 139: Examples of FC reactions applied in F&F industry.
Scheme 140: Continuous-flow synthesis of ibuprofen developed by McQuade et al.
Scheme 141: The FC acylation step of Jamison’s three-step ibuprofen synthesis.
Scheme 142: Synthesis of naphthalene derivative 629 via FC acylation in microreactors.
Scheme 143: Flow system for rapid screening of catalysts and reaction conditions developed by Weber et al.
Scheme 144: Continuous-flow system developed by Buorne, Muller et al. for DSD optimisation of the FC acylation ...
Scheme 145: Continuous-flow FC acylation of alkynes to yield β-chlorovinyl ketones such as 638.
Scheme 146: Continuous-flow synthesis of tonalide (619) developed by Wang et al.
Scheme 147: Continuous-flow preparation of acylated arene such as 290 employing Zr4+-β-zeolite developed by Kob...
Scheme 148: Flow system applied on an Aza-FC reaction catalysed by the thiourea catalyst 648.
Scheme 149: Continuous hydroformylation in scCO2.
Scheme 150: Two-step flow synthesis of aldehyde 655 through a sequential Heck reaction and subsequent hydroform...
Scheme 151: Single-droplet (above) and continuous (below) flow reactors developed by Abolhasani et al. for the ...
Scheme 152: Continuous hydroformylation of 1-dodecene (655) using a PFR-CSTR system developed by Sundmacher et ...
Scheme 153: Continuous-flow synthesis of the aldehyde 660 developed by Eli Lilly & Co. [32]. Adapted with permissio...
Scheme 154: Continuous asymmetric hydroformylation employing heterogenous catalst supported on carbon-based sup...
Scheme 155: Examples of acetylation in F&F industry: synthesis of bornyl (S,R,S-664) and isobornyl (S,S,S-664) ...
Scheme 156: Continuous-flow preparation of bornyl acetate (S,R,S-664) employing the oscillating flow reactor.
Scheme 157: Continuous-flow synthesis of geranyl acetate (666) from acetylation of geraniol (343) developed by ...
Scheme 158: 12-Ttungstosilicic acid-supported silica monolith-catalysed acetylation in flow.
Scheme 159: Continuous-flow preparation of cyclopentenone 676.
Scheme 160: Two-stage synthesis of coumarin (90) via acetylation of salicylaldehyde (88).
Scheme 161: Intensification process for acetylation of 5-methoxytryptamine (677) to melatonin (678) developed b...
Scheme 162: Examples of macrocyclic musky odorants both natural (679–681) and synthetic (682 and 683).
Scheme 163: Flow setup combined with microwave for the synthesis of macrocycle 686 via RCM.
Scheme 164: Continuous synthesis of 2,5-dihydro-1H-pyrroles via ring-closing metathesis.
Scheme 165: Continuous-flow metathesis of 485 developed by Leadbeater et al.
Figure 12: Comparison between RCM performed using different routes for the preparation of 696. On the left the...
Scheme 166: Continuous-flow RCM of 697 employed the solid-supported catalyst 698 developed by Grela, Kirschning...
Scheme 167: Continuous-flow RORCM of cyclooctene employing the silica-absorbed catalyst 700.
Scheme 168: Continuous-flow self-metathesis of methyl oleate (703) employing SILP catalyst 704.
Scheme 169: Flow apparatus for the RCM of 697 using a nanofiltration membrane for the recovery and reuse of the...
Scheme 170: Comparison of loadings between RCMs performed with different routes for the synthesis of 709.
Stereoselective synthesis and transformation of pinane-based 2-amino-1,3-diols
- Ákos Bajtel,
- Mounir Raji,
- Matti Haukka,
- Ferenc Fülöp and
- Zsolt Szakonyi
Beilstein J. Org. Chem. 2021, 17, 983–990, doi:10.3762/bjoc.17.80
- epoxidation of (−)-α-pinene (6), carried out with meta-chloroperoxybenzoic acid (MCPBA), followed by a base-catalyzed allylic rearrangement mediated by aluminium isopropoxide (Al(OiPr)3). The resulting allylic alcohol 7 was reacted with trichloroacetyl isocyanate, followed by alkaline treatment, delivering
Graphical Abstract
Figure 1: Biologically active 2-amino-1,3-diols.
Scheme 1: Stereoselective synthesis of the pinane-fused oxazolidin-2-one 9.
Figure 2: NOESY experiments and X-ray structure elucidation of oxazolidin-2-one 9.
Scheme 2: Stereoselective synthesis of the pinane spiro-fused oxazolidin-2-one 12.
Scheme 3: Parallel synthesis of 2-amino-1,3-diols.
Scheme 4: Synthesis of N-benzyl-2-amino-1,3-diol 16.
Scheme 5: Synthesis of 2-amino-1,3-diols.
Figure 3: NOESY experiments and X-ray structure proofment of the structure of oxazolidine 17.
Scheme 6: Synthesis of 2-phenyliminooxazolidines.
Figure 4: Proposed pathway for the ring–ring tautomerism.
Valorisation of plastic waste via metal-catalysed depolymerisation
- Francesca Liguori,
- Carmen Moreno-Marrodán and
- Pierluigi Barbaro
Beilstein J. Org. Chem. 2021, 17, 589–621, doi:10.3762/bjoc.17.53
Graphical Abstract
Figure 1: Potential classification of plastic recycling processes. The area covered by the present review is ...
Figure 2: EG produced during glycolytic depolymerisation of PET using DEG + DPG as solvent and titanium(IV) n...
Scheme 1: Simplified representation of the conversion of 1,4-PBD to C16–C44 macrocycles using Ru metathesis c...
Figure 3: Main added-value monomers obtainable by catalytic depolymerisation of PET via chemolytic methods.
Scheme 2: Hydrogenolytic depolymerisation of PET by ruthenium complexes.
Scheme 3: Depolymerisation of PET via catalytic hydrosilylation by Ir(III) pincer complex.
Scheme 4: Catalytic hydrolysis (top) and methanolysis (bottom) reactions of PET.
Scheme 5: Depolymerisation of PET by glycolysis with ethylene glycol.
Figure 4: Glycolysis of PET: evolution of BHET yield over time, with and without zinc acetate catalyst (196 °...
Scheme 6: Potential activated complex for the glycolysis reaction of PET catalysed by metallated ILs and evol...
Scheme 7: One-pot, two-step process for PET repurposing via chemical recycling.
Scheme 8: Synthetic routes to PLA.
Scheme 9: Structures of the zinc molecular catalysts used for PLA-methanolysis in various works. a) See [265], b) ...
Scheme 10: Depolymerisation of PLLA by Zn–N-heterocyclic carbene complex.
Scheme 11: Salalen ligands.
Scheme 12: Catalytic hydrogenolysis of PLA.
Scheme 13: Catalytic hydrosilylation of PLA.
Scheme 14: Hydrogenative depolymerisation of PBT and PCL by molecular Ru catalysts.
Scheme 15: Glycolysis reaction of PCT by diethylene glycol.
Scheme 16: Polymerisation–depolymerisation cycle of 3,4-T6GBL.
Scheme 17: Polymerisation–depolymerisation cycle of 2,3-HDB.
Scheme 18: Hydrogenative depolymerisation of PBPAC by molecular Ru catalysts.
Scheme 19: Catalytic hydrolysis (top), alcoholysis (middle) and aminolysis (bottom) reactions of PBPAC.
Scheme 20: Hydrogenative depolymerisation of PPC (top) and PEC (bottom) by molecular Ru catalysts.
Scheme 21: Polymerisation-depolymerisation cycle of BEP.
Scheme 22: Hydrogenolysis of polyamides using soluble Ru catalysts.
Scheme 23: Catalytic depolymerisation of epoxy resin/carbon fibres composite.
Scheme 24: Depolymerisation of polyethers with metal salt catalysts and acyl chlorides.
Scheme 25: Proposed mechanism for the iron-catalysed depolymerisation reaction of polyethers. Adapted with per...
Unexpected rearrangements and a novel synthesis of 1,1-dichloro-1-alkenones from 1,1,1-trifluoroalkanones with aluminium trichloride
- Beatrice Lansbergen,
- Catherine S. Meister and
- Michael C. McLeod
Beilstein J. Org. Chem. 2021, 17, 404–409, doi:10.3762/bjoc.17.36
- of 1,1-dichloro-1-alkenones. The reaction scope was found to be broad, with various chain lengths and aryl substituents tolerated. For substrates containing an electron-rich aromatic ring, further reactions take place, resulting in bicyclic and/or rearrangement products. Keywords: aluminium
- 5m compared to the longer chain substrates (e.g., 5c and 5l) could be explained mechanistically by the formation of a terminal carbocation upon the extraction of a fluorine atom by the aluminium species (Scheme 3). This carbocation could be stabilised to varying degrees by the ketone moiety
Graphical Abstract
Figure 1: Examples of biologically active 1,1-dichloro-1-alkenes.
Figure 2: a) Common methods for the preparation of 1,1-dichloro-1-alkenes from aldehydes. b) This work: a two...
Scheme 1: The initial attempt for the conversion of 1,1,1-trifluoroalkanone 5a to 1,1-dichloroalkenone 6a.
Scheme 2: Substrate scope for the reaction of 1,1,1 trifluoroalkanones with AlCl3. aPurification (normal or r...
Scheme 3: Proposed mechanism for the formation of dichloroalkene 6 from trifluoroalkanone 5.
Scheme 4: Formation of bicyclic ketones 9 and 10 from 1,1,1-trifluoroalkanone 5b using 7 equivalents of AlCl3....
Scheme 5: Conversion of 1,1,1-trifluoroalkanone 5n to acid chloride 13 with AlCl3, and possible mechanism.
Scheme 6: Conversion of 1,1,1-trifluoroalkane 16 to bicycle 17 upon treatment with AlCl3, and possible mechan...
Fluorine effect in nucleophilic fluorination at C4 of 1,6-anhydro-2,3-dideoxy-2,3-difluoro-β-D-hexopyranose
- Danny Lainé,
- Vincent Denavit,
- Olivier Lessard,
- Laurie Carrier,
- Charles-Émile Fecteau,
- Paul A. Johnson and
- Denis Giguère
Beilstein J. Org. Chem. 2020, 16, 2880–2887, doi:10.3762/bjoc.16.237
- evaluated reduction conditions on a simpler difluorinated hexopyranose analogue. Thus, difluoroglucose 21, easily accessible in 3 steps from levoglucosan (1) [21], was subjected to lithium aluminium hydride (LiAlH4) in THF (Scheme 1a) and difluoroglucitol 22 was isolated in 58% yield. The reaction was
Graphical Abstract
Figure 1: Previously described synthesis of 2,3,4-trifluorinated analogues of galactose 6, glucose 7, mannose ...
Figure 2: Typical 19F NMR spectrum (470 MHz, CDCl3) of the crude reaction mixture using Et3N·3HF/Et3N (entry ...
Figure 3: Fluorination at C4 of 1,6-anhydro-2,3-difluorohexopyranose analogues. a) Reactions on triflates 13, ...
Scheme 1: Synthesis of polyfluorinated alditols from levoglucosan 1: a) difluoroglucitol analogue 22; b) trif...
One-pot multicomponent green Hantzsch synthesis of 1,2-dihydropyridine derivatives with antiproliferative activity
- Giovanna Bosica,
- Kaylie Demanuele,
- José M. Padrón and
- Adrián Puerta
Beilstein J. Org. Chem. 2020, 16, 2862–2869, doi:10.3762/bjoc.16.235
- reported by Cao and collaborators [19]. Catalyst characterization and recyclability The catalyst was analyzed by X-ray fluorescence (XRF) spectroscopy in order to ascertain the PW/Al2O3-support ratio. The mass percentage ratio of tungsten, which is the main component of the catalyst, and aluminium, the
Graphical Abstract
Scheme 1: The classical Hantzsch synthesis between benzaldehyde (1a), ethyl acetoacetate (2), and ammonium ac...
Figure 1: Optimization trials with the selected solid catalysts.
Figure 2: Graphical representation of the results obtained in the reusability test.
Activation of pentafluoropropane isomers at a nanoscopic aluminum chlorofluoride: hydrodefluorination versus dehydrofluorination
- Maëva-Charlotte Kervarec,
- Thomas Braun,
- Mike Ahrens and
- Erhard Kemnitz
Beilstein J. Org. Chem. 2020, 16, 2623–2635, doi:10.3762/bjoc.16.213
- 1,1,1,2,3-pentafluoropropane (HFC-245fa, HFC-245cb, and HFC-245eb) were activated through C–F bond activations using aluminium chlorofluoride (ACF) as a catalyst. The addition of the hydrogen source Et3SiH is necessary for the activation of the secondary and tertiary C–F bonds. Multiple C–F bond activations
Graphical Abstract
Scheme 1: Reactivity of tetrafluoropropanes HFO-1234yf (1) (top) and HFO-1234ze (4a) (bottom) in the presence...
Scheme 2: Reactivity of 10a in the presence of ACF as the catalyst in C6D12 (top) or C6D6 (bottom) as solvent...
Scheme 3: Proposed catalytic cycle of the transformation of 10a in C6D12 and C6D6 in the presence of ACF as t...
Scheme 4: Reactivity of 10a in the presence of ACF as the catalyst and HSiEt3 as a hydrogen source in C6D12 (...
Scheme 5: Proposed catalytic cycle for sylilium-mediated hydrodefluorinations and dehydrofluorinations from 1...
Scheme 6: Reactivity of 13 in the presence of ACF as the catalyst, with (top) or without (bottom) HSiEt3 as a...
Scheme 7: Independent reactions starting from 5, 6, or 14 in the presence of ACF as the catalyst.
Scheme 8: Proposed reaction pathways starting from 10a in the presence of ACF and silane.
Scheme 9: Reactivity of 10c in the presence of ACF as the catalyst and 0.5 equivalents of HSiEt3 as a hydroge...
Scheme 10: Proposed catalytic cycles for the transformation of 10c in C6D12 and in the presence of 0.5 equival...
Scheme 11: Reactivity of 10c in the presence of ACF as the catalyst and HSiEt3 as a hydrogen source in C6D12 (...
Scheme 12: Proposed reaction pathways starting from 10c in the presence of ACF and silane.
Scheme 13: Reactivity of 10b in the presence of ACF as the catalyst and HSiEt3 as a hydrogen source in C6D12 (...
Scheme 14: Proposed reaction pathway starting from 10b in the presence of ACF and silane.
Recent developments in enantioselective photocatalysis
- Callum Prentice,
- James Morrisson,
- Andrew D. Smith and
- Eli Zysman-Colman
Beilstein J. Org. Chem. 2020, 16, 2363–2441, doi:10.3762/bjoc.16.197
- ], electron-deficient arenes [24], and nitriles [25]. Additionally, Cozzi recently applied a novel aluminium-based photocatalyst 9 to this reaction, as an earth-abundant metal alternative albeit with slightly reduced enantioselectivities (8 examples, up to 96:4 er) [26]. Interestingly, as with some other
Graphical Abstract
Scheme 1: Amine/photoredox-catalysed α-alkylation of aldehydes with alkyl bromides bearing electron-withdrawi...
Scheme 2: Amine/HAT/photoredox-catalysed α-functionalisation of aldehydes using alkenes.
Scheme 3: Amine/cobalt/photoredox-catalysed α-functionalisation of ketones and THIQs.
Scheme 4: Amine/photoredox-catalysed α-functionalisation of aldehydes or ketones with imines. (a) Using keton...
Scheme 5: Bifunctional amine/photoredox-catalysed enantioselective α-functionalisation of aldehydes.
Scheme 6: Bifunctional amine/photoredox-catalysed α-functionalisation of aldehydes using amine catalysts via ...
Scheme 7: Amine/photoredox-catalysed RCA of iminium ion intermediates. (a) Synthesis of quaternary stereocent...
Scheme 8: Bifunctional amine/photoredox-catalysed RCA of enones in a radical chain reaction initiated by an i...
Scheme 9: Bifunctional amine/photoredox-catalysed RCA reactions of iminium ions with different radical precur...
Scheme 10: Bifunctional amine/photoredox-catalysed radical cascade reactions between enones and alkenes with a...
Scheme 11: Amine/photocatalysed photocycloadditions of iminium ion intermediates. (a) External photocatalyst u...
Scheme 12: Amine/photoredox-catalysed addition of acrolein (94) to iminium ions.
Scheme 13: Dual NHC/photoredox-catalysed acylation of THIQs.
Scheme 14: NHC/photocatalysed spirocyclisation via photoisomerisation of an extended Breslow intermediate.
Scheme 15: CPA/photoredox-catalysed aza-pinacol cyclisation.
Scheme 16: CPA/photoredox-catalysed Minisci-type reaction between azaarenes and α-amino radicals.
Scheme 17: CPA/photoredox-catalysed radical additions to azaarenes. (a) α-Amino radical or ketyl radical addit...
Scheme 18: CPA/photoredox-catalysed reduction of azaarene-derived substrates. (a) Reduction of ketones. (b) Ex...
Scheme 19: CPA/photoredox-catalysed radical coupling reactions of α-amino radicals with α-carbonyl radicals. (...
Scheme 20: CPA/photoredox-catalysed Povarov reaction.
Scheme 21: CPA/photoredox-catalysed reactions with imines. (a) Decarboxylative imine generation followed by Po...
Scheme 22: Bifunctional CPA/photocatalysed [2 + 2] photocycloadditions.
Scheme 23: PTC/photocatalysed oxygenation of 1-indanone-derived β-keto esters.
Scheme 24: PTC/photoredox-catalysed perfluoroalkylation of 1-indanone-derived β-keto esters via a radical chai...
Scheme 25: Bifunctional hydrogen bonding/photocatalysed intramolecular [2 + 2] photocycloadditions of quinolon...
Scheme 26: Bifunctional hydrogen bonding/photocatalysed intramolecular RCA cyclisation of a quinolone.
Scheme 27: Bifunctional hydrogen bonding/photocatalysed intramolecular [2 + 2] photocycloadditions of quinolon...
Scheme 28: Bifunctional hydrogen bonding/photocatalysed [2 + 2] photocycloaddition reactions. (a) First use of...
Scheme 29: Bifunctional hydrogen bonding/photocatalysed deracemisation of allenes.
Scheme 30: Bifunctional hydrogen bonding/photocatalysed deracemisation reactions. (a) Deracemisation of sulfox...
Scheme 31: Bifunctional hydrogen bonding/photocatalysed intramolecular [2 + 2] photocycloaddition of coumarins....
Scheme 32: Bifunctional hydrogen bonding/photocatalysed [2 + 2] photocycloadditions of quinolones. (a) Intramo...
Scheme 33: Hydrogen bonding/photocatalysed formal arylation of benzofuranones.
Scheme 34: Hydrogen bonding/photoredox-catalysed dehalogenative protonation of α,α-chlorofluoro ketones.
Scheme 35: Hydrogen bonding/photoredox-catalysed reductions. (a) Reduction of 1,2-diketones. (b) Reduction of ...
Scheme 36: Hydrogen bonding/HAT/photocatalysed deracemisation of cyclic ureas.
Scheme 37: Hydrogen bonding/HAT/photoredox-catalysed synthesis of cyclic sulfonamides.
Scheme 38: Hydrogen bonding/photoredox-catalysed reaction between imines and indoles.
Scheme 39: Chiral cation/photoredox-catalysed radical coupling of two α-amino radicals.
Scheme 40: Chiral phosphate/photoredox-catalysed hydroetherfication of alkenols.
Scheme 41: Chiral phosphate/photoredox-catalysed synthesis of pyrroloindolines.
Scheme 42: Chiral anion/photoredox-catalysed radical cation Diels–Alder reaction.
Scheme 43: Lewis acid/photoredox-catalysed cycloadditions of carbonyls. (a) Formal [2 + 2] cycloaddition of en...
Scheme 44: Lewis acid/photoredox-catalysed RCA reaction using a scandium Lewis acid between α-amino radicals a...
Scheme 45: Lewis acid/photoredox-catalysed RCA reaction using a copper Lewis acid between α-amino radicals and...
Scheme 46: Lewis acid/photoredox-catalysed synthesis of 1,2-amino alcohols from aldehydes and nitrones using a...
Scheme 47: Lewis acid/photocatalysed [2 + 2] photocycloadditions of enones and alkenes.
Scheme 48: Meggers’s chiral-at-metal catalysts.
Scheme 49: Lewis acid/photoredox-catalysed α-functionalisation of ketones with alkyl bromides bearing electron...
Scheme 50: Bifunctional Lewis acid/photoredox-catalysed radical coupling reaction using α-chloroketones and α-...
Scheme 51: Lewis acid/photocatalysed RCA of enones. (a) Using aldehydes as acyl radical precursors. (b) Other ...
Scheme 52: Bifunctional Lewis acid/photocatalysis for a photocycloaddition of enones.
Scheme 53: Lewis acid/photoredox-catalysed RCA reactions of enones using DHPs as radical precursors.
Scheme 54: Lewis acid/photoredox-catalysed functionalisation of β-ketoesters. (a) Hydroxylation reaction catal...
Scheme 55: Bifunctional copper-photocatalysed alkylation of imines.
Scheme 56: Copper/photocatalysed alkylation of imines. (a) Bifunctional copper catalysis using α-silyl amines....
Scheme 57: Bifunctional Lewis acid/photocatalysed intramolecular [2 + 2] photocycloaddition.
Scheme 58: Bifunctional Lewis acid/photocatalysed [2 + 2] photocycloadditions (a) Intramolecular cycloaddition...
Scheme 59: Bifunctional Lewis acid/photocatalysed rearrangement of 2,4-dieneones.
Scheme 60: Lewis acid/photocatalysed [2 + 2] cycloadditions of cinnamate esters and styrenes.
Scheme 61: Nickel/photoredox-catalysed arylation of α-amino acids using aryl bromides.
Scheme 62: Nickel/photoredox catalysis. (a) Desymmetrisation of cyclic meso-anhydrides using benzyl trifluorob...
Scheme 63: Nickel/photoredox catalysis for the acyl-carbamoylation of alkenes with aldehydes using TBADT as a ...
Scheme 64: Bifunctional copper/photoredox-catalysed C–N coupling between α-chloro amides and carbazoles or ind...
Scheme 65: Bifunctional copper/photoredox-catalysed difunctionalisation of alkenes with alkynes and alkyl or a...
Scheme 66: Copper/photoredox-catalysed decarboxylative cyanation of benzyl phthalimide esters.
Scheme 67: Copper/photoredox-catalysed cyanation reactions using TMSCN. (a) Propargylic cyanation (b) Ring ope...
Scheme 68: Palladium/photoredox-catalysed allylic alkylation reactions. (a) Using alkyl DHPs as radical precur...
Scheme 69: Manganese/photoredox-catalysed epoxidation of terminal alkenes.
Scheme 70: Chromium/photoredox-catalysed allylation of aldehydes.
Scheme 71: Enzyme/photoredox-catalysed dehalogenation of halolactones.
Scheme 72: Enzyme/photoredox-catalysed dehalogenative cyclisation.
Scheme 73: Enzyme/photoredox-catalysed reduction of cyclic imines.
Scheme 74: Enzyme/photocatalysed enantioselective reduction of electron-deficient alkenes as mixtures of (E)/(Z...
Scheme 75: Enzyme/photoredox catalysis. (a) Deacetoxylation of cyclic ketones. (b) Reduction of heteroaromatic...
Scheme 76: Enzyme/photoredox-catalysed synthesis of indole-3-ones from 2-arylindoles.
Scheme 77: Enzyme/HAT/photoredox catalysis for the DKR of primary amines.
Scheme 78: Bifunctional enzyme/photoredox-catalysed benzylic C–H hydroxylation of trifluoromethylated arenes.
Natural dolomitic limestone-catalyzed synthesis of benzimidazoles, dihydropyrimidinones, and highly substituted pyridines under ultrasound irradiation
- Kumar Godugu,
- Venkata Divya Sri Yadala,
- Mohammad Khaja Mohinuddin Pinjari,
- Trivikram Reddy Gundala,
- Lakshmi Reddy Sanapareddy and
- Chinna Gangi Reddy Nallagondu
Beilstein J. Org. Chem. 2020, 16, 1881–1900, doi:10.3762/bjoc.16.156
- , 56.6, 57.6, 60.9, and 64.8° were attributed to the (012), (104), (006), (015), (110), (113), (021), (024), (018), (116), (211), (122), (214), and (030) plane, respectively, of the NDL catalyst (JCPDS card file 5–586: calcite and 11–78: dolomite) [76][77]. Small quantities of aluminium silicates
- bending vibrations of water [82]. The impurities aluminium silicate and iron oxides in the NDL were confirmed by IR spectroscopy. The peaks located at 446, 551, 817, 952, 1247, and 1383 cm−1 were attributed to the Si–O bending, Fe–O stretching, Al–O–Si stretching, Si–OH bending, Si–O stretching, and Al–O
- presence of aluminium silicates and iron oxides present in the sample were confirmed by Raman spectroscopy. The bands at 418, 578, 753, and 985 cm−1 were assigned to Al–O bending, Si–O rocking, Al–O stretching, and Si–OH stretching vibrations, respectively [85]. Further, a very weak peak at 618 cm−1 was
Graphical Abstract
Figure 1: The benzimidazoles I–IV, dihydropyrimidinones/-thiones V–VIII, and 2-amino-4-aryl-3,5-dicarbonitril...
Scheme 1: NDL-catalyzed synthesis of i) 1,2-disubstituted benzimidazoles 3, ii) dihydropyrimidinones/-thiones ...
Figure 2: XRD pattern of the NDL catalyst.
Figure 3: FTIR spectrum of the NDL catalyst.
Figure 4: Raman spectrum of the NDL catalyst.
Figure 5: SEM images of the NDL catalyst.
Figure 6: EDAX analysis of the NDL catalyst.
Scheme 2: Unexpected formation of the bisimine I, 3h, from o-phenylenediamine (1) and salicylaldehyde (2h).
Figure 7: 1H NMR spectrum of 2,2'-((1E,1'E)-(1,2-phenylenebis(azanylylidene))bis (methanylylidene))diphenol (...
Figure 8: XRD pattern of a) the fresh NDL catalyst; b) the recovered NDL catalyst after the 7th cycle of the ...
