First series of N-alkylamino peptoid homooligomers: solution phase synthesis and conformational investigation

• Maxime Pypec,
• Laurent Jouffret,
• Claude Taillefumier and
• Olivier Roy

Beilstein J. Org. Chem. 2022, 18, 845–854, doi:10.3762/bjoc.18.85

• to the mixed anhydride activating method using isobutyl chloroformate (IBCF) in the presence of N-methylmorpholine (NMM) at 0 °C in DMF for 10 min, followed by the addition of hydrazine 1a [43][44]. The best results were obtained with two equivalents of preformed mixed anhydride, pure dimer 2d being

Recent synthesis of thietanes

• Jiaxi Xu

Beilstein J. Org. Chem. 2020, 16, 1357–1410, doi:10.3762/bjoc.16.116

Chemical synthesis of tripeptide thioesters for the biotechnological incorporation into the myxobacterial secondary metabolite argyrin via mutasynthesis

• David C. B. Siebert,
• Roman Sommer,
• Domen Pogorevc,
• Michael Hoffmann,
• Silke C. Wenzel,
• Rolf Müller and
• Alexander Titz

Beilstein J. Org. Chem. 2019, 15, 2922–2929, doi:10.3762/bjoc.15.286

• ′-ethylcarbodiimide hydrochloride, IBCF: isobutyl chloroformate, NMM: N-methylmorpholine, PyBOP: (benzotriazol-1-yloxy)tripyrrolidinophosphonium hexafluorophosphate, SNAc: SCH2CH2NAc, TFFH: fluoro-N,N,N′,N′-tetramethylformamidinium hexafluorophosphate. Chemical structures of naturally occurring argyrins with potent

Versatile synthesis of the signaling peptide glorin

• Robert Barnett,
• Daniel Raszkowski,
• Thomas Winckler and
• Pierre Stallforth

Beilstein J. Org. Chem. 2017, 13, 247–250, doi:10.3762/bjoc.13.27

• and p-toluenesulfonic acid under dehydrating conditions [18]. Opening of the oxazolidinone with sodium ethoxide as nucleophile thus yielded ester 7a, while addition of ethylamine yielded amide 7b. Subsequent amide bond formation with lactam 4 using isobutyl chloroformate or HBTU as coupling reagents

• conditions, 3 h, 76%; d) for 7a: NaOEt, EtOH, 0 °C to rt, 30 min, 76%, for 7b: H2NEt, THF, rt, 16 h, 75%; e) for 8a: isobutyl chloroformate, NMM, 4, DMF, −15 °C to rt, 2 h, 69%, for 8b: HBTU, Et3N, 4, DMSO, rt, 3 h, 69%; f) Pd/C, H2, MeOH, rt, 1 h, 74% 9a, 97% 9b; g) iPr2EtN, DMAP, propionic anhydride, DCM

Total synthesis of (−)-epimyrtine by a gold-catalyzed hydroamination approach

• Thi Thanh Huyen Trinh,
• Khanh Hung Nguyen,
• Patricia de Aguiar Amaral and
• Nicolas Gouault

Beilstein J. Org. Chem. 2013, 9, 2042–2047, doi:10.3762/bjoc.9.242

• of the β-aminoynone 2 began with the Arndt–Eistert homologation [23] of N-Boc-protected D-alanine (Scheme 3). Thus, the N-Boc-D-alanine was treated with isobutyl chloroformate at 0 °C in THF/diethyl ether followed by the addition of diazomethane to afford the corresponding diazoketone. The Wolff

A scalable synthesis of the (S)-4-(tert-butyl)-2-(pyridin-2-yl)-4,5-dihydrooxazole ((S)-t-BuPyOx) ligand

• Hideki Shimizu,
• Jeffrey C. Holder and
• Brian M. Stoltz

Beilstein J. Org. Chem. 2013, 9, 1637–1642, doi:10.3762/bjoc.9.187

• reaction mixture was cooled to 0 °C in an ice bath and isobutyl chloroformate (3.14 g, 23.0 mmol, 1.15 equiv) was added dropwise over 30 min. Following complete addition, the reaction mixture was stirred for 30 min at 0 °C. In a separate flask, (S)-tert-leucinol (2.58 g, 22.0 mmol, 1.10 equiv) was

Preparation of mixed trialkyl alkylcarbonate derivatives of etidronic acid via an unusual route

• Petri A. Turhanen,
• Janne Weisell and
• Jouko J. Vepsäläinen

Beilstein J. Org. Chem. 2012, 8, 2019–2024, doi:10.3762/bjoc.8.228

• etidronate and alkyl chloroformate was developed by utilizing unexpected demethylation and decarboxylation reactions. The reaction with the sterically more hindered isobutyl chloroformate at a lower temperature (90 °C) produced the P,P'-diester (2) as a stable intermediate product. A possible reaction

• when either methyl or isobutyl chloroformate was used in the reaction under reflux; invariably the three corresponding esters and one alkoxycarbonyl group were observed in the phosphorous ends with a tertiary hydroxy derived with an alkoxycarbonyl group. Another unexpected reaction was observed when

• compound 1 was treated with isobutyl chloroformate at 90 °C (see Scheme 2). After workup procedure from the 31P NMR spectrum we detected only one symmetric product, which was confirmed to be compound 2 according to a subsequent mass-spectrometric analysis. The reaction from 1 to 3b was also tested under

Synthesis of trifunctional cyclo-β-tripeptide templates

• Frank Stein,
• Tahir Mehmood,
• Tilman Plass,
• Javid H. Zaidi and
• Ulf Diederichsen

Beilstein J. Org. Chem. 2012, 8, 1576–1583, doi:10.3762/bjoc.8.180

• prepared from the respective β-amino acids by Arndt–Eistert homologation [17][18][19]. The β-amino acids were transformed into the respective diazoketones with isobutyl chloroformate, triethylamine and diazomethane. The ketones were further converted into the β-amino acids by Wolff rearrangement using

• solution was cooled at −15 °C and dry triethylamine (4.19 mL, 29.8 mmol, 1.10 equiv) and isobutyl chloroformate (3.91 mL, 29.8 mmol, 1.10 equiv) were slowly added and the whole mixture was stirred for 45 min. The reaction mixture was warmed to 0 °C, and under exclusion of light an approximately 0.35 M

Kinetic evaluation of the solvolysis of isobutyl chloro- and chlorothioformate esters

• Malcolm J. D’Souza,
• Matthew J. McAneny,
• Dennis N. Kevill,
• Jin Burm Kyong and
• Song Hee Choi

Beilstein J. Org. Chem. 2011, 7, 543–552, doi:10.3762/bjoc.7.62

• & Applied Chemistry, Hanyang University, Ansan-si, Gyeonggi-do, 426-791, Korea 10.3762/bjoc.7.62 Abstract The specific rates of solvolysis of isobutyl chloroformate (1) are reported at 40.0 °C and those for isobutyl chlorothioformate (2) are reported at 25.0 °C, in a variety of pure and binary aqueous

• suggestion that side-by-side addition–elimination and ionization mechanisms operate, and the relative importance is dependent on the type of chloro- or chlorothioformate substrate and the solvent. Keywords: addition–elimination; Grunwald–Winstein equations; ionization; isobutyl chloroformate; isobutyl

• conformation where the halogen atom is in a trans position with respect to the alkyl group. In Figure 1, the molecular structures for syn-isobutyl chloroformate (1), syn-isobutyl chlorothioformate (2), phenyl chloroformate (3), phenyl chlorodithioformate (4), and isopropyl chloroformate (5), and their

Synthesis of glycosylated β³-homo-threonine conjugates for mucin-like glycopeptide antigen analogues

• Florian Karch and
• Anja Hoffmann-Röder

Beilstein J. Org. Chem. 2010, 6, No. 47, doi:10.3762/bjoc.6.47

• by Norgren et al. [29]. TN antigen derivative Fmoc-Thr(αAc3GalNAc)-OH (1a) was prepared according to published procedures [32][33] and converted into the corresponding diazo ketone upon treatment with isobutyl chloroformate in the presence of N-methylmorpholine (NMM) and diazomethane (Scheme 1

Synthesis of (S)-1-(2-chloroacetyl)pyrrolidine- 2-carbonitrile: A key intermediate for dipeptidyl peptidase IV inhibitors

• Santosh K. Singh,
• Narendra Manne and
• Manojit Pal

Beilstein J. Org. Chem. 2008, 4, No. 20, doi:10.3762/bjoc.4.20

• well in the literature. Thus, the acid 8 was treated with a number of reagents [e.g. (i) ethyl chloroformate / Et3N or (ii) isobutyl chloroformate / Et3N or (iii) SOCl2 or oxalyl chloride] separately followed by aqueous ammonia in the same pot. However, in all these cases the desired amide was isolated