Recent advances in the tandem annulation of 1,3-enynes to functionalized pyridine and pyrrole derivatives

• Yi Liu,
• Puying Luo,
• Yang Fu,
• Tianxin Hao,
• Xuan Liu,
• Qiuping Ding and
• Yiyuan Peng

Beilstein J. Org. Chem. 2021, 17, 2462–2476, doi:10.3762/bjoc.17.163

• structural motifs to provide the functionalized pyridine and pyrrole derivatives. The functionalization reactions cover iodination, bromination, trifluoromethylation, azidation, carbonylation, arylation, alkylation, selenylation, sulfenylation, amidation, esterification, and hydroxylation. We also briefly

On the application of 3d metals for C–H activation toward bioactive compounds: The key step for the synthesis of silver bullets

• Renato L. Carvalho,
• Amanda S. de Miranda,
• Mateus P. Nunes,
• Roberto S. Gomes,
• Guilherme A. M. Jardim and
• Eufrânio N. da Silva Júnior

Beilstein J. Org. Chem. 2021, 17, 1849–1938, doi:10.3762/bjoc.17.126

• Streptomyces lasaliensis cultures [195]. The synthesis succeeded in five steps, each one of them in good yields, including the cobalt-catalyzed C–H bond addition (Scheme 37D). One year later, the same group described a unique cobalt-Cp* catalyzed C(sp2)–H amidation technique [196] applied to thiostrepton (125

• same year, Wu, Li and co-workers described a successful cobalt-Cp*-catalyzed C–H amidation of benzaldehyde derivatives (Scheme 39B), in which the aldehyde portion works as the directing group [198]. After an acid workup using diluted hydrochloric acid, the desired ortho-amidated products were obtained

[2 + 1] Cycloaddition reactions of fullerene C₆₀ based on diazo compounds

• Yuliya N. Biglova

Beilstein J. Org. Chem. 2021, 17, 630–670, doi:10.3762/bjoc.17.55

• methanofullerene-appended dicarboxylic acid 85 synthesized from 10 is a versatile synthon for conversion into numerous derivatives (Scheme 25). The reactivity of compound 85 was studied under DCC-promoted esterification conditions (see adducts 8 and 86) and amidation conditions (see adducts 21 and 22). Hummelen

Deoxygenative C2-heteroarylation of quinoline N-oxides: facile access to α-triazolylquinolines

• Geetanjali S. Sontakke,
• Rahul K. Shukla and
• Chandra M. R. Volla

Beilstein J. Org. Chem. 2021, 17, 485–493, doi:10.3762/bjoc.17.42

• secondary amines as the nucleophiles [49]. In their protocol, the regioselectivity is controlled by PyBroP catalyst, which acts as the N-oxide activator. Manley and Bilodeau reported the amidation of heterocyclic N-oxides at the C2-position using oxalyl chloride for activating the N-oxides [50]. In addition

• to amination and amidation, there are few reports on metal-free C2-heteroarylation of pyridine N-oxides. In 1984, Rogers demonstrated the synthesis of 2-triazolylpyridines from 2-azidopyridines and phenylacetylene [51]. Along the same lines, Keith reported methodologies for the C2-imidazolylation and

Supramolecular polymerization of sulfated dendritic peptide amphiphiles into multivalent L-selectin binders

• David Straßburger,
• Svenja Herziger,
• Katharina Huth,
• Moritz Urschbach,
• Rainer Haag and
• Pol Besenius

Beilstein J. Org. Chem. 2021, 17, 97–104, doi:10.3762/bjoc.17.10

• -mediated amidation of Boc-protected tri-ʟ-phenylalanine, as β-sheet directing peptide sequence, afforded the peptide amphiphile in good yields. After deprotection of the N-terminus with TFA, molecule 4 was suitable for coupling to the branching unit to obtain the desired dendritic peptide amphiphiles. In

• case of the C3-symmetric amphiphile I, the readily available benzene-1,3,5-tricarboxylic acid (trimesic acid) was chosen as the branching unit. In the final amidation reaction, the efficient PyBOP-mediated coupling was carried out using an excess of the peptide amphiphile. Finally, the target compound

Progress in the total synthesis of inthomycins

• Bidyut Kumar Senapati

Beilstein J. Org. Chem. 2021, 17, 58–82, doi:10.3762/bjoc.17.7

• % yield. Finally, compound (+)-76 underwent amidation and deacetylation to give an 11.1:1 mixture of geometrical isomers of inthomycin C ((−)-3) in 77% yield over two steps (Scheme 17) [50]. The (3R) stereochemistry of (−)-3 was confirmed by MTPA ester derivatization, which supports the recent work by

• (+)-147a followed by Pinnick oxidation afforded the acid (+)-148a. Finally, the EDCl-mediated amidation of unstable acid (+)-148a followed by debenzoylation produced inthomycin A ((+)-1). Similarly, compound (+)-146b was converted into inthomycin B ((+)-2) (Scheme 25). To complete the total synthesis of

Syntheses of spliceostatins and thailanstatins: a review

• William A. Donaldson

Beilstein J. Org. Chem. 2020, 16, 1991–2006, doi:10.3762/bjoc.16.166

• -methyl-3-buten-1-yl tosylate in the presence of Grubbs’ 2nd generation catalyst yielded 59, which, upon elimination with potassium tert-butoxide led to the diene 50. The reductive amination of 50 afforded an inseparable mixture of the C-14 amines (6:1 ratio). However, the amidation of this mixture with

• transformations, prior to the cleavage of the Boc amide protecting group. The free amine 118 underwent an amidation with the TBS-protected (2Z,4S)-4-hydroxy-2-butenoic acid 12b to give 119. The modified Julia olefination of the aldehyde 73 with the anion derived from 119 proceeded with a high E-selectivity to

• the use of a Ru-catalyzed olefin cross-metathesis for the generation of the dienyl segment joining the two tetrahydropyranyl segments (Scheme 20) [12][13]. The cleavage of the Boc amide of 31 and the eventual amidation with (2Z,4S)-4-acetoxy-2-butenoic acid (12c) gave 121. The construction of the

Photocatalyzed syntheses of phenanthrenes and their aza-analogues. A review

• Alessandra Del Tito,
• Havall Othman Abdulla,
• Davide Ravelli,
• Stefano Protti and
• Maurizio Fagnoni

Beilstein J. Org. Chem. 2020, 16, 1476–1488, doi:10.3762/bjoc.16.123

• oxidative C–H amidation, offering a straightforward access to phenanthridones (Scheme 18). The process took place upon blue LED irradiation (20–24 h at 60 °C were required) of the chosen substrates (e.g., 18.1a–d) in the presence of the Ir-based photoredox catalyst Ir[dF(CF3)ppy]2(bpy)PF6 (2.5 mol %) and a

• -cyanobiaryl)acrylamides 17.1a–d. The direct oxidative C–H amidation involving amidyl radicals for the synthesis of phenanthridones. Funding Havall Othman Abdulla is grateful to the Chemistry Department, College of Science, Salahaddin University‐Erbil (Iraq) for financial support.

Recent applications of porphyrins as photocatalysts in organic synthesis: batch and continuous flow approaches

• Rodrigo Costa e Silva,
• Luely Oliveira da Silva,
• Aloisio de Andrade Bartolomeu,
• Timothy John Brocksom and
• Kleber Thiago de Oliveira

Beilstein J. Org. Chem. 2020, 16, 917–955, doi:10.3762/bjoc.16.83

• thermal decomposition of urea at 550 °C for 2 h afforded the CN polymer, which possesses abundant –NH2 functional groups. The heterogeneous photocatalyst carbon nitride-hemin (CNH) was prepared after an amidation reaction between a carboxyl group of Fe(III) protoporphyrin IX and an amino group of the CN

Efficient synthesis of piperazinyl amides of 18β-glycyrrhetinic acid

• Dong Cai,
• ZhiHua Zhang,
• Yufan Meng,
• KaiLi Zhu,
• LiYi Chen,
• ChangXiang Yu,
• ChangWei Yu,
• ZiYi Fu,
• DianShen Yang and
• YiXia Gong

Beilstein J. Org. Chem. 2020, 16, 798–808, doi:10.3762/bjoc.16.73

• for the construction of important intermediate 8 are discussed. One procedure involves the amidation of 1-Boc-piperazine with 3-acetyl-18β-glycyrrhetinic acid, prepared by the reaction of 18β-glycyrrhetinic acid with acetic anhydride without any solvent at 130 °C. The other procedure to prepare

• compound 8 involves the amidation of 18β-glycyrrhetinic acid followed by the esterification with acetic anhydride. Finally, compound 8 underwent N-Boc deprotection to prepare product 4. To ascertain the scope of the reaction, another C-3 ester derivative 17 was tested under the optimized reaction

• two methods are complicated through the side formation of bisamide, obviously, due to the competitive attack on the N atoms of the symmetric diamine. An alternative method [12] to prepare such piperazinyl amides (c) involves the amidation of 18β-glycyrrhetinic acid with 4-substituted phenylpiperazines

Combining enyne metathesis with long-established organic transformations: a powerful strategy for the sustainable synthesis of bioactive molecules

• Valerian Dragutan,
• Ileana Dragutan,
• Albert Demonceau and
• Lionel Delaude

Beilstein J. Org. Chem. 2020, 16, 738–755, doi:10.3762/bjoc.16.68

• in the pyrrolidine ring catalyzed by RhCl3·H2O, followed by debenzylation, amidation, and aminal generation using the Stille protocol [77]. (–)‐Clavukerin A and related sesquiterpenes Applying original organocatalytic/metal-catalyzed tactics, Metz et al. [78] reported a tandem dienyne RCM for the

Exploring the scope of DBU-promoted amidations of 7-methoxycarbonylpterin

• Anna R. Bockman and
• Jeffrey M. Pruet

Beilstein J. Org. Chem. 2020, 16, 509–514, doi:10.3762/bjoc.16.46

• yields often >80%. Keywords: amidation; DBU; folate; pterin; Introduction Pteridines are a class of fused bicyclic heterocycles with significant biological relevance. The 2-amino-4-pteridinone core, simply referred to as “pterin”, is present in various biological cofactors like folates, biopterin, and

• reaction by employing a pseudo-first order kinetics model. Furthermore, we adapted the reaction to allow for reaction times as little as 5 minutes, with yields reaching up to 99%. Results and Discussion The general procedure for the DBU-promoted amidation involved the initial suspension of 7-CMP (1) in a

• amines to be adequately reassessed on their ease of amidation (Table 2). It was found that the reaction was most affected by an α-substitution on the amine (Table 2; products 11–13). This is in agreement with known Taft parameters which show steric effects are more pronounced for an isopropyl group

A review of asymmetric synthetic organic electrochemistry and electrocatalysis: concepts, applications, recent developments and future directions

• Munmun Ghosh,
• Valmik S. Shinde and
• Magnus Rueping

Beilstein J. Org. Chem. 2019, 15, 2710–2746, doi:10.3762/bjoc.15.264

• involved the synthesis of precursor (+)-198 from phenylacetic acid and (−)-α-PEA via sequential amidation, reduction and Pictet–Spengler cyclization reactions. The key anodic oxidation in the presence of NaCN converted (+)-198 to α-amino nitrile (+)-199 with excellent diastereoselectivity. Upon further

Targeted photoswitchable imaging of intracellular glutathione by a photochromic glycosheet sensor

• Xianzhi Chai,
• Hai-Hao Han,
• Yi Zang,
• Jia Li,
• Xiao-Peng He,
• Junji Zhang and
• He Tian

Beilstein J. Org. Chem. 2019, 15, 2380–2389, doi:10.3762/bjoc.15.230

• 4 according to reported methods [27]. Then, the photochromic fluorophore intermediate 7 was synthesized by coupling compounds 3 and 6 through amidation. The Glyco-DTE reporter was prepared by click reaction between compound 7 and acetylated β-ᴅ-galactoside, followed by deacetylation. Similarly, a

1,2,3-Triazolium macrocycles in supramolecular chemistry

• Mastaneh Safarnejad Shad,
• Pulikkal Veettil Santhini and
• Wim Dehaen

Beilstein J. Org. Chem. 2019, 15, 2142–2155, doi:10.3762/bjoc.15.211

• macroring. A second strategy is the macrocyclization of an acyclic precursor containing pre-functionalized triazole by other ring closure methods such as Grubbs metathesis [25] and amidation reactions. The macrocyclization is normally followed by N-alkylation (often methylation) leading to the synthesis of

A metal-free approach for the synthesis of amides/esters with pyridinium salts of phenacyl bromides via oxidative C–C bond cleavage

• Kesari Lakshmi Manasa,
• Yellaiah Tangella,
• Namballa Hari Krishna and
• Mallika Alvala

Beilstein J. Org. Chem. 2019, 15, 1864–1871, doi:10.3762/bjoc.15.182

• of a C–C bond followed by formation of a new C–N/C–O bond in the presence of K2CO3. Various pyridinium salts of phenacyl bromides can be readily transformed into a variety of amides and esters which is an alternative method for the conventional amidation and esterification in organic synthesis. High

• functional group tolerance, broad substrate scope and operational simplicity are the prominent advantages of the current protocol. Keywords: amidation; benzoylation; benzylamines; pyridinium salt of phenacyl bromides; Introduction Amidation and esterification are fundamental transformations in synthetic

Recent advances on the transition-metal-catalyzed synthesis of imidazopyridines: an updated coverage

• Gagandeep Kour Reen,
• Ashok Kumar and
• Pratibha Sharma

Beilstein J. Org. Chem. 2019, 15, 1612–1704, doi:10.3762/bjoc.15.165

• -catalyzed cross-coupling reactions have laid down the foundation of new C–C bond formations [50][51]. A number of Pd-catalyzed organic reactions viz., C–N coupling, amination and intramolecular amidation, cyclization, and Suzuki–Miyaura coupling [52][53][54][55] have recently been reported in the literature

• single-electron transfer (SET) with CuI followed by hydride abstraction/intramolecular nucleophilic addition and loss of a proton forming the desired compound 49 (Scheme 19). Cu(I)-catalyzed intramolecular oxidative C–H amidation of N-pyridylenaminones 61 for the synthesis of imidazo[1,2-a]pyridine

A chemically contiguous hapten approach for a heroin–fentanyl vaccine

• Yoshihiro Natori,
• Candy S. Hwang,
• Lucy Lin,
• Lauren C. Smith,
• Bin Zhou and
• Kim D. Janda

Beilstein J. Org. Chem. 2019, 15, 1020–1031, doi:10.3762/bjoc.15.100

• soluble KLH or BSA solution (Figures S2–S7, Supporting Information File 1). Concerned by the possibility that the alcohols on glycerol would outcompete amidation, we tested several concentrations of glycerol in the range of 10–50% (w/w). Based on MALDI–TOF data and as expected, the conjugation with the

Diaminoterephthalate–α-lipoic acid conjugates with fluorinated residues

• Leon Buschbeck,
• Aleksandra Markovic,
• Gunther Wittstock and
• Jens Christoffers

Beilstein J. Org. Chem. 2019, 15, 981–991, doi:10.3762/bjoc.15.96

• sequence including one deprotection reaction. One functional unit is α-lipoic acid (ALA) for binding the dye to gold surfaces. It was introduced to the DAT scaffold by an amidation reaction. The other functional unit is a para-(trifluoromethyl)benzyl group for facile detection of the surface-bound material

• amidation using a standard coupling protocol (with COMU–DIPEA). Compound 3 was accessed in 60% yield over three steps. In solution (CH2Cl2), 3 shows strong fluorescence (quantum yield Φ = 57%) at λem = 495 nm when irradiated at its absorption maximum at λmax = 420 nm. In order to achieve bathochromic shifts

Synthesis of acylglycerol derivatives by mechanochemistry

• Karen J. Ardila-Fierro,
• Andrij Pich,
• Marc Spehr,
• José G. Hernández and
• Carsten Bolm

Beilstein J. Org. Chem. 2019, 15, 811–817, doi:10.3762/bjoc.15.78

• targeted the mechanosynthesis of the DAGs by reacting MAG 4a and fatty acids 3 in the ball mill. Such esterifications required the activation of 3 with N,N’-dicyclohexylcarbodiimide (DCC), thereby complementing other recently developed solvent-free carboxylic acid activations towards amidation or

Selective benzylic C–H monooxygenation mediated by iodine oxides

• Kelsey B. LaMartina,
• Haley K. Kuck,
• Linda S. Oglesbee,
• Asma Al-Odaini and
• Nicholas C. Boaz

Beilstein J. Org. Chem. 2019, 15, 602–609, doi:10.3762/bjoc.15.55

• catalytic NHPI and iodic acid mediated the hydroxylation or amidation of tertiary C–H bonds using either wet nitromethane or dry acetonitrile, respectively [54][55]. The substrate scope of the developed benzylic C–H monooxygenation reaction was examined via the oxidation of substrates containing benzylic C

Syntheses and chemical properties of β-nicotinamide riboside and its analogues and derivatives

• Mikhail V. Makarov and
• Marie E. Migaud

Beilstein J. Org. Chem. 2019, 15, 401–430, doi:10.3762/bjoc.15.36

• corresponding N-alkyl-nicotinamides. A more reactive 2,3,5-tri-O-acetyl-β-phenyl nicotinate riboside 20 was therefore generated. To limit transesterification and favor amidation, trifluoroethanol was used as solvent instead of methanol, and as a result, amides 21 were prepared in good yields (Scheme 11). In

Reusable and highly enantioselective water-soluble Ru(II)-Amm-Pheox catalyst for intramolecular cyclopropanation of diazo compounds

• Hamada S. A. Mandour,
• Yoko Nakagawa,
• Masaya Tone,
• Hayato Inoue,
• Nansalmaa Otog,
• Ikuhide Fujisawa,
• Soda Chanthamath and
• Seiji Iwasa

Beilstein J. Org. Chem. 2019, 15, 357–363, doi:10.3762/bjoc.15.31

• the catalyst leakage during the work-up. Synthetic transformations of 2d and 2f In order to demonstrate the advantages of products, further synthetic transformations of the cyclopropane products were investigated. A ring opening and direct amidation of the chiral cyclopropane-fused γ-lacton 2d using

Synthesis of unnatural α-amino esters using ethyl nitroacetate and condensation or cycloaddition reactions

• Glwadys Gagnot,
• Vincent Hervin,
• Eloi P. Coutant,
• Sarah Desmons,
• Racha Baatallah,
• Victor Monnot and
• Yves L. Janin

Beilstein J. Org. Chem. 2018, 14, 2846–2852, doi:10.3762/bjoc.14.263

• in Scheme 5, the oxazole-bearing α-amino ester 43 was prepared from the aspartic acid derivative 37 through the propargylamide 38 followed by a gold(I)-catalyzed cyclization to form the oxazoline derivative 40. Concerning the amidation step, propargylamide 38 was obtained in 78% yield provided that

Synergistic approach to polycycles through Suzuki–Miyaura cross coupling and metathesis as key steps

• Sambasivarao Kotha,
• Milind Meshram and
• Chandravathi Chakkapalli

Beilstein J. Org. Chem. 2018, 14, 2468–2481, doi:10.3762/bjoc.14.223

• derivative 134 was realized in the presence of a Pd(OAc)2 catalyst with the aid of the ligand cataCXium A (135) to generate the macrocyclic product 136. Eventually, synthesis of MK-6325 (141) was achieved by adopting saponification followed by amidation (Scheme 20). Conclusion In this review, we have