Selective formation of a zwitterion adduct and bicarbonate salt in the efficient CO₂ fixation by N-benzyl cyclic guanidine under dry and wet conditions

• Yoshiaki Yoshida,
• Naoto Aoyagi and
• Takeshi Endo

Beilstein J. Org. Chem. 2018, 14, 2204–2211, doi:10.3762/bjoc.14.194

• fixation of CO2 such as cycloaddition of CO2 to various epoxides and synthesis of carbonate derivatives from CO2 and alcohols [6][7][8][9][10][11][12][13]. However, these kinds of catalysts often need high temperatures and pressure to completely achieve the CO2 fixation [6]. On the other hand, amidine and

Studies towards the synthesis of hyperireflexolide A

• G. Hari Mangeswara Rao

Beilstein J. Org. Chem. 2018, 14, 2106–2111, doi:10.3762/bjoc.14.185

• 13C NMR spectra were recorded at 100 MHz (125 MHz) on a JEOL spectrometer. Samples for NMR were made in CDCl3. Tetramethylsilane was used as the internal standard. Commercial grade solvents were distilled before use. Ethyl acetate was distilled over anhydrous sodium carbonate. Dichloromethane and

Applications of organocatalysed visible-light photoredox reactions for medicinal chemistry

• Michael K. Bogdos,
• Emmanuel Pinard and
• John A. Murphy

Beilstein J. Org. Chem. 2018, 14, 2035–2064, doi:10.3762/bjoc.14.179

• ) using atmospheric oxygen as the stoichiometric oxidant, TBA-Eosin Y photocatalysis and carbonate as the base at room temperature (Scheme 23) [68]. The group also reported that this transformation is possible using sunlight as the source of photons, with a yield comparable to that obtained when blue LEDs

• for application to LSF. Leonori et al. have demonstrated the coupling of amide derivatives to aromatics using aryloxy amides, under Eosin Y photocatalysis with green LEDs and potassium carbonate (Scheme 30) [74]. The reaction is well suited for LSF, as is demonstrated by the authors in the

Defining the hydrophobic interactions that drive competence stimulating peptide (CSP)-ComD binding in Streptococcus pneumoniae

• Bimal Koirala,
• Robert A. Hillman,
• Erin K. Tiwold,
• Michael A. Bertucci and
• Yftah Tal-Gan

Beilstein J. Org. Chem. 2018, 14, 1769–1777, doi:10.3762/bjoc.14.151

• -galactopyranoside (ONPG) at a final concentration of 0.4 mg/mL was added, followed by 100 µL of lysate, and the plate was incubated for 3 hours at 37 ºC. The reaction was stopped by adding 50 µL of 1 M sodium carbonate solution, and the OD420nm and OD550nm were measured using a plate reader. The final results were

An amine protecting group deprotectable under nearly neutral oxidative conditions

• Shahien Shahsavari,
• Chase McNamara,
• Mark Sylvester,
• Emily Bromley,
• Savannah Joslin,
• Bao-Yuan Lu and
• Shiyue Fang

Beilstein J. Org. Chem. 2018, 14, 1750–1757, doi:10.3762/bjoc.14.149

• base potassium carbonate at room temperature. The products were then purified with flash column chromatography. As shown in Table 1, the yields of the deprotection ranged from 48% to 88%. Among them, 3a and 3d, which are aliphatic amines, gave better yields (Table 1, entries 1 and 4). Compounds 3b and

• conditions (Table 1, entry 9). In the β-elimination step, when methanol was used as the solvent as in the general deprotection procedure, no reaction occurred even after stirring overnight. This might be caused by the more favoured deprotonation of the carboxylic acid group by potassium carbonate, which made

• diamine 10 in 75% isolated yield (Scheme 2). The basic conditions involving potassium carbonate used to induce β-elimination of oxidized dM-Dmoc did not cause any loss of Fmoc protection. Conclusion In summary, we have demonstrated that dM-Dmoc could serve as a new protecting group for aliphatic and

β-Hydroxy sulfides and their syntheses

• Mokgethwa B. Marakalala,
• Edwin M. Mmutlane and
• Henok H. Kinfe

Beilstein J. Org. Chem. 2018, 14, 1668–1692, doi:10.3762/bjoc.14.143

• mixture of potassium carbonate and potassium bicarbonate in 95:5 water–methanol at 23 °C for 12 h proceeded quantitatively to afford the product leukotriene C-1 (Scheme 42). The epoxide 120 has been the key intermediate in all syntheses of LTC4, -D4, and -E4; upon exposure to the desired amino acid, it

Direct electrochemical generation of organic carbonates by dehydrogenative coupling

• Tile Gieshoff,
• Vinh Trieu,
• Jan Heijl and
• Siegfried R. Waldvogel

Beilstein J. Org. Chem. 2018, 14, 1578–1582, doi:10.3762/bjoc.14.135

• reactive chemicals. We present the first direct electrochemical generation of mesityl methyl carbonate by C–H activation. Although this reaction pathway is still challenging concerning scope and efficiency, it outlines a new strategy for carbonate generation. Keywords: anode; boron-doped diamond

• carbonates like diphenyl carbonate (DPC) or dimethyl carbonate (DMC) are key intermediates. Processes for the carbonate generation have been investigated since the 1950s [2]. Although the use of these starting materials is straightforward and unobjectionable at first sight, their generation usually requires

• highly reactive chemicals. This comes with disadvantages in high safety requirements for handling these chemicals, such as ethylene oxide and phosgene [3]. Alternative approaches to carbonate generation are oxidative carbonylations or dehydrative condensations based on alcohols as starting materials

Hypervalent organoiodine compounds: from reagents to valuable building blocks in synthesis

• Gwendal Grelier,
• Benjamin Darses and
• Philippe Dauban

Beilstein J. Org. Chem. 2018, 14, 1508–1528, doi:10.3762/bjoc.14.128

• metal-free alternative to the previous methods of formation of sulfur heterocycles 70 has been reported by using elemental sulfur in the presence of cesium carbonate (Scheme 32) [72]. The strategy can be extended to the synthesis of the cyclic selenium analogs 71 by utilizing elemental selenium and

• domino process for the introduction of both aromatic rings of diaryl-λ3-iodanes, though a small excess of this reagent is needed to obtain good yields. An initial N-arylation reaction of 3,5-dimethylpyrazole is performed in the presence of potassium carbonate, in xylene at 70 °C, releasing 1 equivalent

Spectroelectrochemical studies on the effect of cations in the alkaline glycerol oxidation reaction over carbon nanotube-supported Pd nanoparticles

• Dennis Hiltrop,
• Steffen Cychy,
• Karina Elumeeva,
• Wolfgang Schuhmann and
• Martin Muhler

Beilstein J. Org. Chem. 2018, 14, 1428–1435, doi:10.3762/bjoc.14.120

• varying the potential between 0.77 and 1.17 V vs RHE: at low potentials oxidized C3 species such as mesoxalate and tartronate were formed predominantly, and with increasing potentials C2 and C1 species originating from C–C bond cleavage were identified. The tendency to produce carbonate was found to be

• less pronounced in KOH. The less favored formation of highly oxidized C3 species and of carbonate is deduced to be the origin of the lower current densities in the cyclic voltammograms (CVs) for Pd/NCNT in KOH. The enhanced current densities in NaOH are rationalized by the presence of Na+ ions bound to

• the IR beam on the working electrode surface through a thin electrolyte layer probing vibrations of adsorbed intermediates and products [12]. Highly active catalysts converting glycerol to carbonate consume 20 hydroxide ions per glycerol molecule in the thin electrolyte layer, which leads to a

Novel unit B cryptophycin analogues as payloads for targeted therapy

• Eduard Figueras,
• Adina Borbély,
• Mohamed Ismail,
• Marcel Frese and
• Norbert Sewald

Beilstein J. Org. Chem. 2018, 14, 1281–1286, doi:10.3762/bjoc.14.109

• conjugation of the novel cryptophycin analogues across an appropriate linker to an antibody or peptide. Either a virtually uncleavable triazole (introduced by CuAAC) or scissile ester, carbonate, or carbamate moieties were taken into account. The synthesis of the modified unit B (Scheme 1) started with the

One hundred years of benzotropone chemistry

• Arif Dastan,
• Haydar Kilic and
• Nurullah Saracoglu

Beilstein J. Org. Chem. 2018, 14, 1120–1180, doi:10.3762/bjoc.14.98

Selective carboxylation of reactive benzylic C–H bonds by a hypervalent iodine(III)/inorganic bromide oxidation system

• Toshifumi Dohi,
• Shohei Ueda,
• Kosuke Iwasaki,
• Yusuke Tsunoda,
• Koji Morimoto and
• Yasuyuki Kita

Beilstein J. Org. Chem. 2018, 14, 1087–1094, doi:10.3762/bjoc.14.94

• stirred solution of arylalkane 1 (0.50 mmol) and acetic acid (0.57 mL, ca. 10 mmol) in dry dichloromethane (5 mL). Then the mixture was vigorously stirred at 40 °C with or without zinc acetate (92 mg, 0.5 mmol). After checking the reaction completion by TLC, saturated aqueous sodium carbonate was added to

• the mixture and the resulting solution was stirred for an additional 5 min. The organic layer was separated, washed again with saturated aqueous sodium carbonate, then with dilute aqueous sodium thiosulfate, and was dried over anhydrous sodium sulfate. After removal of the solvents, the residue was

• (ca. 2.5 mmol) with freshly-dried molecular sieves 3 Å (ca. 300 mg) in dry dichloromethane (5 mL). Then the mixture was vigorously stirred at 40 °C. After checking the reaction completion by TLC, saturated aqueous sodium carbonate was added to the mixture and the resulting solution was stirred for an

Mechanochemistry of nucleosides, nucleotides and related materials

• Olga Eguaogie,
• Joseph S. Vyle,
• Patrick F. Conlon,
• Manuela A. Gîlea and
• Yipei Liang

Beilstein J. Org. Chem. 2018, 14, 955–970, doi:10.3762/bjoc.14.81

• ) and adenosine diphosphate ribose (ADPR) was also described. Subsequently, this methodology was applied to the preparation of a library of six ADPR carbonate derivatives in 23–68% yields (e.g., Scheme 14) and tested as sirtuin inhibitors [54]. The efficiency of phosphate coupling under mechanochemical

On the design principles of peptide–drug conjugates for targeted drug delivery to the malignant tumor site

• Eirinaios I. Vrettos,
• Gábor Mező and
• Andreas G. Tzakos

Beilstein J. Org. Chem. 2018, 14, 930–954, doi:10.3762/bjoc.14.80

• unit (EHU; colored in green) and to a tumor-targeting element (i.e. tumor homing peptide; colored in black). The alcohol group at the opposite site can be connected via a carbonate ester/carbamate bond to the cytotoxic agent (colored in blue). The EHU is designed so as to be a substrate for proteases

An uracil-linked hydroxyflavone probe for the recognition of ATP

• Márton Bojtár,
• Péter Zoltán Janzsó-Berend,
• Dávid Mester,
• Dóra Hessz,
• Mihály Kállay,
• Miklós Kubinyi and
• István Bitter

Beilstein J. Org. Chem. 2018, 14, 747–755, doi:10.3762/bjoc.14.63

• mode. Synthetic procedures 1-(2-Hydroxy-4-(prop-2-yn-1-yloxy)phenyl)ethanone (1) [61]: The propargyl compound 1 was synthesized as described with a modified purification method. 1-(2,4-dihydroxyphenyl)ethanone (6.00 g, 39.4 mmol, Sigma) was dissolved in acetone (90 mL). Potassium carbonate (6.54 g

Volatiles from the xylarialean fungus Hypoxylon invadens

• Jeroen S. Dickschat,
• Tao Wang and
• Marc Stadler

Beilstein J. Org. Chem. 2018, 14, 734–746, doi:10.3762/bjoc.14.62

• hydroxy-methylbenzaldehydes were converted into the corresponding methoxy derivatives by methylation with potassium carbonate and methyl iodide. The GC–MS analysis of all the obtained methylation products unequivocally established the identity of 17 and 2-methoxy-4-methylbenzaldehyde by the same retention

• -one (19) According to Okombi et al. [27], potassium carbonate (1.38 g, 10.0 mmol) was added to a solution of 2,6-dihydroxyacetophenone (23, 304 mg, 2.0 mmol) in acetone (10 mL), and the mixture was stirred at room temperature for 15 minutes. Then, acetyl chloride (157 mg, 2.0 mmol) was added and

Liquid-assisted grinding and ion pairing regulates percentage conversion and diastereoselectivity of the Wittig reaction under mechanochemical conditions

• Kendra Leahy Denlinger,
• Lianna Ortiz-Trankina,
• Preston Carr,
• Kingsley Benson,
• Daniel C. Waddell and
• James Mack

Beilstein J. Org. Chem. 2018, 14, 688–696, doi:10.3762/bjoc.14.57

• . Results and Discussion Liquid-assisted grinding To focus the study, benzaldehyde, benzyl bromide, polymer-supported triphenylphosphine (PS-C6H4-PPh2) and potassium carbonate were ball-milled in a stainless steel vial with two LAG solvents at opposite ends of the dielectric spectrum, as well as a control

• that Cs+ and Br− would be a good pair, since their values are similar. We would expect Rb+ to pair well with Br− for the same reason. To test this idea and to understand the effect of the interaction, we conducted the solvent-free polymer-supported Wittig reaction with various carbonate salts and alkyl

• , and 5 indicates that the carbonate bases deprotonated the phosphonium salt to form the ylide which then subsequently added to the benzaldehyde. However, the oxygen anion could not bind to the phosphorus cation to produce the stilbene product, presumably due to the mismatched counter ion pair. After

AuBr₃-catalyzed azidation of per-O-acetylated and per-O-benzoylated sugars

• Jayashree Rajput,
• Srinivas Hotha and
• Madhuri Vangala

Beilstein J. Org. Chem. 2018, 14, 682–687, doi:10.3762/bjoc.14.56

• purine and pyrimidine nucleoside synthesis using per-O-acyl/per-O-benzoyl furanosyl and pyranosyl o-hexynylbenzoates [23]. Subsequently, Hotha and co-workers utilized propargyl 1,2-orthoesters and alkynyl glycosyl carbonate donors for the synthesis of pyrimidine nucleosides [24][25]. In addition, N

High-yielding continuous-flow synthesis of antimalarial drug hydroxychloroquine

• Eric Yu,
• Hari P. R. Mangunuru,
• Nakul S. Telang,
• Caleb J. Kong,
• Jenson Verghese,
• Stanley E. Gilliland III,
• Saeed Ahmad,
• Raymond N. Dominey and
• B. Frank Gupton

Beilstein J. Org. Chem. 2018, 14, 583–592, doi:10.3762/bjoc.14.45

• carbonate at 100 °C. The output solution was collected and quenched with a saturated solution of ammonium chloride. The aqueous phase was extracted by DCM (3 × 50 mL) and the organic layers were combined, dried over sodium sulfate, and evaporated in vacuo to give a light brown liquid (14.05 g, 86%). 1H NMR

• -(ethylamino)ethan-1-ol (7) in THF solution (1.0 M) were streamed in at 0.5 mL min−1 via a T-piece into a 10 mL reactor coil (tR =10 min) and passed through a packed bed reactor of potassium carbonate. The output solution was streamlined with hydroxylamine (1.0 M) at 1.0 mL min−1 via a T-piece into a 10 mL

• reactor coil (tR =10 min) and passed through a packed bed reactor of potassium carbonate at 100 °C. The reaction mixture was then concentrated in vacuo, taken up in dichloromethane (3 × 20 mL) and concentrated under reduced pressure to yield 11 as light brown liquid. The crude product was used in the next

Synthesis and stability of strongly acidic benzamide derivatives

• Frederik Diness,
• Niels J. Bjerrum and
• Mikael Begtrup

Beilstein J. Org. Chem. 2018, 14, 523–530, doi:10.3762/bjoc.14.38

• , 137.6, 132.23, 131.9, 127.6, 121.02 (q, J = 319.3 Hz); 19F NMR (470 MHz, MeOD) δ −80.60 (s); HRMS (TOF) m/z: [M − H]− calcd for C9H479BrF6N2O4S2−, 460.8706; found. 460.8766. 4-(1H-Benzo[d]imidazol-1-yl)-N-((trifluoromethyl)sulfonyl)benzamide (13): Cesium carbonate (163 mg, 5 equiv) was added to a glass

• closed screw cap vial to 100 °C for 1 min (color changed from yellow to deep red). A part of the catalyst mixture (0.2 mL) was added to a microwave glass vial containing a degassed mixture of 9d (33.1 mg, 0.1 mmol), 4-methoxyphenylboronic acid (22.8 mg, 0.15 mmol, 1.5 equiv) and cesium carbonate (100 mg

5-Aminopyrazole as precursor in design and synthesis of fused pyrazoloazines

• Ranjana Aggarwal and
• Suresh Kumar

Beilstein J. Org. Chem. 2018, 14, 203–242, doi:10.3762/bjoc.14.15

• in presence of bis(pentafluorophenyl) carbonate (BPC) as activating agent (Scheme 46). Abdelhamid et al. [106] reported the synthesis of pyrazolo[1,5-a]pyrimidine derivatives 168 from the reaction of 5-aminopyrazoles 16/126 with sodium 3-(5-methyl-1-phenyl-1H-pyrazol-4-yl)-3-oxoprop-1-en-1-olate (167

• iodomethane in acetone in the presence of potassium carbonate to give methyl thioether 188 which provided hydrazinopyrazolo[3,4-d]pyrimidines 189 on treatment with an excess of hydrazine hydrate in ethanol. The hydrazine derivative 189 thus obtained was made to react with several carbonyl compounds like

Photocatalytic formation of carbon–sulfur bonds

• Alexander Wimmer and
• Burkhard König

Beilstein J. Org. Chem. 2018, 14, 54–83, doi:10.3762/bjoc.14.4

• conditions were not suitable for aliphatic alkynes as they do not undergo oxidative addition with the [NiI] sulfide complex. Miyake and co-workers described a very different approach for the C–S cross-coupling between aryl thiols and aryl halides (Scheme 24) [59]. In a mixture with caesium carbonate as a

Aminosugar-based immunomodulator lipid A: synthetic approaches

• Alla Zamyatina

Beilstein J. Org. Chem. 2018, 14, 25–53, doi:10.3762/bjoc.14.3

• migration and/or elimination of the secondary acyl chain. TfOH-mediated 1,2-trans glycosylation smoothly provided β(1→6)-linked diglucosamine, the free OH group in position 3 was protected as Alloc carbonate and the benzylidene acetal protecting group was regioselectively reductively opened to furnish 6’-O

The photodecarboxylative addition of carboxylates to phthalimides as a key-step in the synthesis of biologically active 3-arylmethylene-2,3-dihydro-1H-isoindolin-1-ones

• Ommid Anamimoghadam,
• Saira Mumtaz,
• Anke Nietsch,
• Gaetano Saya,
• Cherie A. Motti,
• Jun Wang,
• Peter C. Junk,
• Ashfaq Mahmood Qureshi and
• Michael Oelgemöller

Beilstein J. Org. Chem. 2017, 13, 2833–2841, doi:10.3762/bjoc.13.275

• ][44][45][46]. Results and Discussion Initial irradiation experiments were conducted with N-(2-bromoethyl)phthalimide (1a) and potassium phenylacetate (2a) as a model system (Scheme 2 and Table 1). The salt 2a, generated from the corresponding phenylacetic acid and potassium carbonate, was used in

• ca. 8.7 at the end of the irradiation. Temperature control was crucial as thermal conversion of 3a into 4 was found to occur above 40 °C. Compound 1a could be converted quantitatively to the oxazolidine derivative 4 by treatment with either sodium carbonate or potassium tert-butoxide in acetonitrile

• compound 1a was treated with either sodium carbonate or potassium tert-butoxide it was indeed converted quantitatively to the oxazolidine derivative 4. Similarly, the final benzylated hydroxyphthalimidine may undergo cyclization instead (path C), as was found to occur at elevated temperature of >40 °C

Vinylphosphonium and 2-aminovinylphosphonium salts – preparation and applications in organic synthesis

• Anna Kuźnik,
• Roman Mazurkiewicz and
• Beata Fryczkowska

Beilstein J. Org. Chem. 2017, 13, 2710–2738, doi:10.3762/bjoc.13.269

• Wehman (Scheme 4) [10]. Vinylphosphonium salts can also be prepared by alkylation of phosphines (usually triphenylphosphine) with allyl halide derivatives and isomerization of allylphosphonium salts 4 thus obtained under the influence of bases such as triethylamine or sodium carbonate (Scheme 5) [11][12

• method for obtaining vinylphosphonium salts consists in the one-step electrochemical oxidation of triphenylphosphine in the presence of cycloalkenes. The synthesis of 1-cycloalkenetriphenylphosphonium salts 19 was carried out in the presence of 2,6-lutidine perchlorate and anhydrous potassium carbonate