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

Hydroarylations by cobalt-catalyzed C–H activation

• Rajagopal Santhoshkumar and
• Chien-Hong Cheng

Beilstein J. Org. Chem. 2018, 14, 2266–2288, doi:10.3762/bjoc.14.202

• the transformations is the addition of C–H to C–X multiple bonds to afford alkylation, alkenation, amidation, and cyclization products using low- or high-valent cobalt catalysts. This hydroarylation is an efficient approach to build new C–C bonds in a 100% atom-economical manner. In this review, the

• functionalization. Of these reactions, alkylation, alkenation, amidation, and cyclization of arenes with the relevant coupling partners are an economical and straightforward approach for the synthesis of diverse alkyls, alkenes, amides and cyclic compounds. A simple addition of a “inert” C–H bond to multiple bonds

• a similar C–H amidation reaction of aryl pyrazoles 64 with isocyanates in the presence of [CoCp*(C6H6)](PF6)2 and KOAc [101]. Conclusion Hydroarylation is an emerging methodology in organic synthesis, because it is a highly atom-, step-, and redox-economical and simple reaction compared to

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

Functionalization of graphene: does the organic chemistry matter?

• Artur Kasprzak,
• Agnieszka Zuchowska and
• Magdalena Poplawska

Beilstein J. Org. Chem. 2018, 14, 2018–2026, doi:10.3762/bjoc.14.177

• Artur Kasprzak Agnieszka Zuchowska Magdalena Poplawska Faculty of Chemistry, Warsaw University of Technology, Noakowskiego Str. 3, 00-664 Warsaw, Poland 10.3762/bjoc.14.177 Abstract Reactions applying amidation- or esterification-type processes and diazonium salts chemistry constitute the most

• commonly applied synthetic approaches for the modification of graphene-family materials. This work presents a critical assessment of the amidation and esterification methodologies reported in the recent literature, as well as a discussion of the reactions that apply diazonium salts. Common

• areas of research, including colloid chemistry and interface science; nevertheless, the basic rules of organic chemistry should be regarded as playing a leading role in covalent functionalization. Review Reactions of carboxyl groups: amidation, esterification A primary amine or a primary alcohol

Design, synthesis and structure of novel G-2 melamine-based dendrimers incorporating 4-(n-octyloxy)aniline as a peripheral unit

• Cristina Morar,
• Pedro Lameiras,
• Attila Bende,
• Gabriel Katona,
• Emese Gál and
• Mircea Darabantu

Beilstein J. Org. Chem. 2018, 14, 1704–1722, doi:10.3762/bjoc.14.145

• 7a and 7b (Scheme 4) by the triple amidation of trimesic acid trichloride upon treatment with G-1 dendron D-N

  NH (covalent m-trimerisation →7a) or by simple neutralisation of the latter with trimesic acid (ionic m-trimerisation →7b), the product of which was symbolised as [D-N

  NH2+]3(−OOC)3C6H3

Synthesis of diamido-bridged bis-pillar[5]arenes and tris-pillar[5]arenes for construction of unique [1]rotaxanes and bis-[1]rotaxanes

• Ying Han,
• Li-Ming Xu,
• Cui-Yun Nie,
• Shuo Jiang,
• Jing Sun and
• Chao-Guo Yan

Beilstein J. Org. Chem. 2018, 14, 1660–1667, doi:10.3762/bjoc.14.142

• sequential alkylation of ω-bromoalkoxy-substituted pillar[5]arenes with methyl or ethyl p-hydroxybenzoate followed by a hydrolytic reaction under basic conditions. Under catalysis of HOBt/EDCl, the amidation reaction of pillar[5]arene mono(oxybutoxy)benzoic acid with monoamido-functionalized pillar[5]arenes

• afforded diamido-bridged bis-pillar[5]arenes. 1H NMR and 2D NOESY spectra clearly indicated that [1]rotaxanes were formed by insertion of longer diaminoalkylene unit into the cavity of one pillar[5]arene with another pillar[5]arene acting as a stopper. The similar catalysed amidation reaction of pillar[5

• have a longer chain functionalized group and a large macrocycle, which enabled them to be a good candidate as an efficient terminal stopper for the construction of rotaxanes. Therefore, the amidation reaction of pillar[5]arene mono(oxybutoxy)benzoic acid 3a with our previously reported amido

Thiocarbonyl-enabled ferrocene C–H nitrogenation by cobalt(III) catalysis: thermal and mechanochemical

• Santhivardhana Reddy Yetra,
• Zhigao Shen,
• Hui Wang and
• Lutz Ackermann

Beilstein J. Org. Chem. 2018, 14, 1546–1553, doi:10.3762/bjoc.14.131

• manifold. Keywords: amidation; C–H activation; cobalt; ferrocene; mechanochemistry; Introduction C–H activation has surfaced as a transformative tool in molecular sciences [1][2][3][4][5][6][7][8][9]. While major advances have been accomplished with precious 4d transition metals, recent focus has shifted

• and Discussion We initiated our studies by probing various reaction conditions for the envisioned C–H amidation of ferrocene 1a (Table 1). Among a variety of ligands, N-heterocyclic carbenes and phosphines provided unsatisfactory results (Table 1, entries 1–3), while the product 3aa was formed when

• essential nature of the cobalt catalyst (Table 1, entry 13). In contrast to the thiocarbonyl-assisted C–H amidation, the corresponding ketone failed thus far to deliver the desired product, under otherwise identical reaction conditions. With the optimized reaction conditions in hand, we explored the

Oligonucleotide analogues with cationic backbone linkages

• Melissa Meng and
• Christian Ducho

Beilstein J. Org. Chem. 2018, 14, 1293–1308, doi:10.3762/bjoc.14.111

• . After the desired number of such coupling-deprotection cycles, the phosphite-linked oligo-thymidine 16 was transformed in an oxidative amidation reaction [42] in the presence of iodine and N,N,N'-trimethylethylenediamine (17) to yield, after basic cleavage from the solid support, the envisioned

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

• α,β-unsaturated aldehyde 71. A series of reductive amination and amidation reactions then led to the formation of the targeted substituted benzo[7]annulene 72 (Scheme 13). Moreover, the structure–activity study revealed that some of the compounds showed nano- to subnanomolar IC50 values on αvβ3 and

Recyclable hypervalent-iodine-mediated solid-phase peptide synthesis and cyclic peptide synthesis

• Dan Liu,
• Ya-Li Guo,
• Jin Qu and
• Chi Zhang

Beilstein J. Org. Chem. 2018, 14, 1112–1119, doi:10.3762/bjoc.14.97

• mediated by hypervalent iodine(III) reagents in recent years. In 2012, for the first time, we reported that the hypervalent iodine(III) reagent iodosodilactone (Figure 1) can serve as a condensing reagent to promote esterification, macrolactonization, amidation and peptide coupling reactions in the