Solid-phase synthesis of biaryl bicyclic peptides containing a 3-aryltyrosine or a 4-arylphenylalanine moiety

• Iteng Ng-Choi,
• Àngel Oliveras,
• Lidia Feliu and
• Marta Planas

Beilstein J. Org. Chem. 2019, 15, 761–768, doi:10.3762/bjoc.15.72

• 9-fluorenylmethoxycarbonyl (Fmoc)/tert-butyl (t-Bu) strategy (Scheme 2). The non-commercially available amino acids Boc-Phe(4-BPin)-OH, Fmoc-Phe(4-I)-OH and Fmoc-Glu-OpNB were prepared in solution. Boc-Phe(4-BPin)-OH was obtained from Boc-Phe(4-I)-OH [27] through esterification, Miyaura borylation

Synthesis of the polyketide section of seragamide A and related cyclodepsipeptides via Negishi cross coupling

• Jan Hendrik Lang and
• Thomas Lindel

Beilstein J. Org. Chem. 2019, 15, 577–583, doi:10.3762/bjoc.15.53

• recent synthesis of plusbacin A3, Ichikawa et al. experienced similar difficulties when attempting esterification of a bulky β-OTIPS-substituted amino acid with a secondary alcohol under a variety of conditions [49]. Conclusion We developed a short synthesis of the polyketide building block present in

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

• the N1 atom of Nam occurs under these conditions. Hydrolytic de-esterification of 9a,b was achieved by a treatment with an anhydrous ammonia methanolic solution at −5 °C. Removal of benzoyl groups required prolonged reaction times (48 h versus 6 h for acetyl groups). It should be also noted that in

• after de-esterification of the tribenzoate intermediate ( +25°) using methanol saturated with dry ammonia at 2 °C for 2 days (content of β-anomer was <3%, as determined by enzymatic analyses). This result may be explained by the fact that 2,3,5-tri-O-benzoyl-D-ribofuranosylamine – although prepared by

• synthetic sequence, the key reaction of which was a coupling of bisphosphonate 34 with isopropylidene-protected NR+ 29 under the Steglich esterification conditions in the presence of tri-n-octylamine, pyridine and DCC in DMF medium at 60 °C for 18 h (Scheme 19). Compound 36 was isolated in pure form by

Synthesis of nonracemic hydroxyglutamic acids

• Dorota G. Piotrowska,
• Iwona E. Głowacka,
• Andrzej E. Wróblewski and
• Liwia Lubowiecka

Beilstein J. Org. Chem. 2019, 15, 236–255, doi:10.3762/bjoc.15.22

• )-5 which after O-benzylation provided an inseparable 1:3 mixture of compounds 8a and 8b. A six-carbon chain was shortened by a diol formation–diol cleavage sequence followed by aldehyde oxidation and esterification to give 9a and 9b after chromatographic separation. They were transformed into (2S,3R

• removal of the chiral auxiliary with simultaneous formation of a N-Boc derivative 30. The hydroxymethyl to carboxylate transformation to form the protected diester (2S,3R)-31 required prior basic deacetylation followed by standard oxidation and esterification. Diastereoisomer (2S,3S)-31 was also prepared

• nitrogen was protected as N-Boc to furnish (4R,5R)-47. Under basic conditions the pyrrolidin-2-one ring was cleaved to provide a five-carbon chain of the target molecule. The final steps included esterification, desilylation and selective oxidation of the hydroxymethyl group followed by esterification

Gold-catalyzed ethylene cyclopropanation

• Silvia G. Rull,
• Andrea Olmos and
• Pedro J. Pérez

Beilstein J. Org. Chem. 2019, 15, 67–71, doi:10.3762/bjoc.15.7

• ], electroreductive dehalogenation [7] and decarboxylation of diethyl 1,1-cyclopropyldicarboxylate [8]. Other methods include the transesterification of other alkyl cyclopropanecarboxylates [9] and the esterification with ethanol of the cyclopropanecarboxylic acid [10]. This product finds applications as lubricant

Selective ring-opening metathesis polymerization (ROMP) of cyclobutenes. Unsymmetrical ladderphane containing polycyclobutene and polynorbornene strands

• Yuan-Zhen Ke,
• Shou-Ling Huang,
• Guoqiao Lai and
• Tien-Yau Luh

Beilstein J. Org. Chem. 2019, 15, 44–51, doi:10.3762/bjoc.15.4

• linker is because the ester group could be selectively hydrolyzed in the presence of amides. This selectivity will be helpful for the structural elucidation of polymer 8. Thus, 10b was allowed to react with 11 to afford amide-alcohol 12 in 79% yield. Esterification of 12 with 13b furnished 70% yield of

An overview on recent advances in the synthesis of sulfonated organic materials, sulfonated silica materials, and sulfonated carbon materials and their catalytic applications in chemical processes

• Hashem Sharghi,
• Pezhman Shiri and
• Mahdi Aberi

Beilstein J. Org. Chem. 2018, 14, 2745–2770, doi:10.3762/bjoc.14.253

• sulfonated polymer-carbon nanotubes composites (CNT-P-SO3H) 100–102 were described as outstanding catalysts for liquid phase transesterification of triglycerides 103 with methanol. The catalysts were also used for the esterification of oleic acid (106) with methanol. The important feature of this study is

• temperature. The esterification of long chain-free fatty acids with methanol was performed well for 10–12 h (Scheme 20). To check the effect of acid groups, HMP-1 (113) was also used as a catalyst for the reaction and low yields of corresponding products were obtained [68]. In another study, a new microporous

• sulfonated by concentrated sulfuric acid or p-toluenesulfonic acid (Scheme 24) [73]. The catalytic applications of these sulfonated carbon catalysts were investigated in the esterification of oleic acid with methanol (with different ratios of MeOH/oleic acid) at 70 °C for 2 h. Theoretically, the

Cobalt- and rhodium-catalyzed carboxylation using carbon dioxide as the C1 source

• Tetsuaki Fujihara and
• Yasushi Tsuji

Beilstein J. Org. Chem. 2018, 14, 2435–2460, doi:10.3762/bjoc.14.221

• -phenanthroline) as the catalyst, 4a-Me was obtained in 86% yield after esterification. Other bidentate ligands such as bpy, phen, and dppe were not suitable for this reaction. Control experiments revealed that both the Co catalyst and the Mn reductant were indispensable to the reaction. The carboxylation of

• 14e containing a bicyclo[2.2.2]octane framework with ketone and dimethyl ketal moieties was also converted and the corresponding product was isolated as the methyl ester 15e-Me after esterification. For the Co-catalyzed C(sp3)–H carboxylation of allylarenes, a mechanism shown in Scheme 13 can be

A switchable [2]rotaxane with two active alkenyl groups

• Xiu-Li Zheng,
• Rong-Rong Tao,
• Rui-Rui Gu,
• Wen-Zhi Wang and
• Da-Hui Qu

Beilstein J. Org. Chem. 2018, 14, 2074–2081, doi:10.3762/bjoc.14.181

• and treated with NaBH4, protected by di-tert-butyl pyrocarbonate to get compound 3. The esterification reaction was carried out subsequently between hydroxy compound 3 and allylacetic acid to afford compound 4, which was further reacted with CF3COOH and followed by the anion exchange in the methyl

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

Anomeric modification of carbohydrates using the Mitsunobu reaction

• Julia Hain,
• Patrick Rollin,
• Werner Klaffke and
• Thisbe K. Lindhorst

Beilstein J. Org. Chem. 2018, 14, 1619–1636, doi:10.3762/bjoc.14.138

• achieve good results in the Mitsunobu procedure. We have reviewed on the one hand the literature on anomeric esterification, including glycosyl phosphates, and on the other hand glycoside synthesis, including S- and N-glycosides. The mechanistic details of the Mitsunobu reaction are discussed as well as

• , they can also be manipulated to one’s advantage, for example for the stereoselective formation of β-mannosides [28]. Reactions with protic acids to achieve anomeric esters The first application of the Mitsunobu reaction involved esterification of a secondary alcohol. Although an anomeric OH group

• -D-glucuronide products could be isolated in up to 50% yield. Similarly, regioselective esterification of unprotected allyl glucuronide 11 was performed by Juteau et al. with the acids 12–16 yielding anomeric mixtures of the respective 1-O-acyl-β-D-glucuronides 18–22 in quite acceptable yields even

Acyl-group specificity of AHL synthases involved in quorum-sensing in Roseobacter group bacteria

• Lisa Ziesche,
• Jan Rinkel,
• Jeroen S. Dickschat and
• Stefan Schulz

Beilstein J. Org. Chem. 2018, 14, 1309–1316, doi:10.3762/bjoc.14.112

• with cysteamine into the protected thiol 8 [39]. Steglich esterification [40] with different free acids led to nine saturated PCEs 10a–i, four monounsaturated acids (11a–d), 3-OH-C10:0-HSL PCE (12), and 2E,11Z-C18:2-PCE (13) after deprotection with acetic acid [41]. Although compounds 10–13 can be

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

• and A succeeded as previously described in the literature; unit A (15) and C–D (16) were connected by Yamaguchi esterification to give 17 (Scheme 2) [45]. Then, Fmoc was cleaved from the N-terminus of unit C–D–A (17) using piperidine and the resulting crude amine was coupled to the corresponding

A survey of chiral hypervalent iodine reagents in asymmetric synthesis

• Soumen Ghosh,
• Suman Pradhan and
• Indranil Chatterjee

Beilstein J. Org. Chem. 2018, 14, 1244–1262, doi:10.3762/bjoc.14.107

• with excellent enantioselectivity (Scheme 2d). Another class of chiral I(V) reagents 6 was synthesized by Wirth et al. who synthesized the desired compounds through esterification between chiral alcohols and the I(I)-substituted aromatic acids followed by oxidation with dimethyldioxirane (Scheme 2e

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

Preparation, structure, and reactivity of bicyclic benziodazole: a new hypervalent iodine heterocycle

• Akira Yoshimura,
• Michael T. Shea,
• Cody L. Makitalo,
• Melissa E. Jarvi,
• Gregory T. Rohde,
• Akio Saito,
• Mekhman S. Yusubov and
• Viktor V. Zhdankin

Beilstein J. Org. Chem. 2018, 14, 1016–1020, doi:10.3762/bjoc.14.87

• ; biheterocycles; hypervalent iodine; iodine; oxidatively assisted esterification; Introduction In recent years, the interest in heterocyclic organohypervalent iodine compounds has experienced an unprecedented growth [1][2][3][4][5][6]. A variety of new hypervalent iodine heterocycles have been prepared, and

• ), which is in agreement with the previously proposed mechanism of oxidatively assisted esterification or amidation [23][38]. Conclusion In summary, we have prepared the new bicyclic benziodazole 7a by the oxidation of 2-iodo-N,N’-diisopropylisophthalamide (6a) with m-CPBA. The solid structure of 7a was

• (1)–N(1) 2.177 (4) Å; N(1)–I(1)–C(1) 76.89 (18)°; N(2)–I(1)–C(1) 77.02 (18)°; N(1)–I(1)–N(2) 153.90 (15)°. Representative examples of benziodoxoles and benziodazoles. Preparation of bicyclic benziodazole 7a. Benziodadiazole 7a mediated oxidatively assisted esterification and amidation reactions

Polysubstituted ferrocenes as tunable redox mediators

• Sven D. Waniek,
• Jan Klett,
• Christoph Förster and
• Katja Heinze

Beilstein J. Org. Chem. 2018, 14, 1004–1015, doi:10.3762/bjoc.14.86

• application as redox mediator (Scheme 2) [55][56]. Ferrocenyl esters 1–4 are synthetically accessible via the acids of 1 [45][46], 2 [57], 3 and 4 [54] in a direct selective metalation of ferrocene [54][57][58][59][60], quenching with carbon dioxide, followed by esterification [45][46][47][48][54]. The 1,1

Volatiles from three genome sequenced fungi from the genus Aspergillus

• Jeroen S. Dickschat,
• Ersin Celik and
• Nelson L. Brock

Beilstein J. Org. Chem. 2018, 14, 900–910, doi:10.3762/bjoc.14.77

• an even number of carbons are much more widespread. Furthermore, esterification with S-adenosyl-l-methionine (SAM) by a methyltransferase is a very common process in nature, while ethyl esters are rarer and likely require a two-step pathway through reduction of acetyl-CoA to ethanol and its

• esterification by an acyl transferase. In Neurospora crassa acids of short chain alcohols are formed from alcohols and aldehydes via hemiacetals that are oxidised to the corresponding esters by an alcohol dehydrogenase [43]. The main compounds were ethyl pentanoate (35) and ethyl heptanoate (37), accompanied by

• small amounts of ethyl hexanoate (36), ethyl octanoate (38) and the unsaturated ester ethyl (Z)-hept-4-enoate (41) that was unambiguously identified by synthesis of a reference compound by esterification of (Z)-hept-4-enoic acid with ethanol. A compound with the retention index I = 1090 was reported

Nanoreactors for green catalysis

• M. Teresa De Martino,
• Loai K. E. A. Abdelmohsen,
• Floris P. J. T. Rutjes and
• Jan C. M. van Hest

Beilstein J. Org. Chem. 2018, 14, 716–733, doi:10.3762/bjoc.14.61

• ) was encapsulated in the lumen of the polymersomes or in the Pickering emulsion water droplet. The esterification reaction of 1-hexanol and hexanoic acid was used to evaluate the catalytic performance of the CalB-loaded Pickering emulsions. Higher enzymatic activity was observed when CalB was

Latest development in the synthesis of ursodeoxycholic acid (UDCA): a critical review

• Fabio Tonin and
• Isabel W. C. E. Arends

Beilstein J. Org. Chem. 2018, 14, 470–483, doi:10.3762/bjoc.14.33

• oxidized in position C12 to the corresponding ketone, after which Wolff–Kishner reduction can be applied. This whole sequence comprises 5 steps [13]. After the protection of the carboxylic group by acid-catalyzed esterification (quantitative yield), the 3- and 7-OH groups are protected selectively with

• an infinitesimal change in the number of electrons [61]. The overall yield of the epimerization step is around 70% [12][15][62]. A further purification step is necessary for the preparation of free UDCA: it can be easily obtained with sequential esterification, extraction and hydrolysis (yield 91

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

• (5H)-one derivatives 204 by refluxing in 1 N sodium hydroxide. Pyrazolo[3,4-d]pyrimidinone 204 were further chlorinated by phosphorus oxychloride and subsequently converted to carboxylic esters 207 via cyanation followed by hydrolysis and esterification. Kaplan et al. [20] explored the synthesis of

Volatiles from the tropical ascomycete Daldinia clavata (Hypoxylaceae, Xylariales)

• Tao Wang,
• Kathrin I. Mohr,
• Marc Stadler and
• Jeroen S. Dickschat

Beilstein J. Org. Chem. 2018, 14, 135–147, doi:10.3762/bjoc.14.9

• compound 9. This compound was synthesised by esterification of pent-4-en-2-ol (31) with acryloyl chloride (32) to 33, followed by ring-closing metathesis using the Hoveyda–Grubbs catalyst of the second generation (Scheme 8). The synthetic material proved to be identical to the volatile of D. clavata

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

• concept [32] (Scheme 4b) [34]. They first introduced alkene moieties to the chemically inert lignin structure by esterification of the hydroxy groups of lignin with 4-pentenoic acid. Subsequent radical thiol–ene reaction with aliphatic thiols, using [Ru(bpy]3Cl2 as photocatalyst and p-toluidine as redox

Aminosugar-based immunomodulator lipid A: synthetic approaches

• Alla Zamyatina

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

Recent progress in the racemic and enantioselective synthesis of monofluoroalkene-based dipeptide isosteres

• Myriam Drouin and
• Jean-François Paquin

Beilstein J. Org. Chem. 2017, 13, 2637–2658, doi:10.3762/bjoc.13.262

• )-monofluoroalkenes (Scheme 6) [32][33]. HWE olefination promoted by Mg(II) of (diethoxyphosphoryl)fluoroacetic acid (25) with triisopropylsilyl-protected 2-hydroxymethylcyclopentanone 26 was realized with excellent yield and stereoselectivity. Esterification of the resulting carboxylic acid 27 into the corresponding