Synthesis of<i>β</i>-D-Ribofuranosyl-(1→3)-<i>α</i>-L-rhamnopyranosyl-(1→3)-L-rhamnopyranose by in situ Activating Glycosylation Using 1-OH Sugar Derivative and Me<sub>3</sub>SiBr–CoBr<sub>2</sub>–Bu<sub>4</sub>NBr–Molecular Sieves 4A System
β-d-Ribofuranosyl-(1→3)-α-l-rhamnopyranosyl-(1→3)-l-rhamnopyranose, the trisaccharide repeating unit of the C. freundii O28,1c O-specific polysaccharide, was synthesized using in situ activating glycosylation of the 1-OH sugar derivatives and a reagent mixture of trimethylsilyl bromide, cobalt(II) bromide, tetrabutylammonium bromide, and molecular sieves 4A. Regioselective tritylation was useful for synthesizing the 3-OH derivatives of methyl, allyl, and benzyl α-l-rhamnosides.
Total Synthesis of the Potent and Broad-Spectrum Antibiotics Amycolamicin and Kibdelomycin
作者:Shaoqiang Yang、Chenglong Chen、Jie Chen、Chao Li
DOI:10.1021/jacs.1c11477
日期:2021.12.22
complex and intriguing structures of the antibiotics amycolamicin and kibdelomycin are herein confirmed through totalsynthesis. Careful titration of the synthetic products reveals that kibdelomycin is the salt form of amycolamicin. This synthesis employs a highly convergent strategy, which provides a modular approach for further SAR studies of this class of antibiotics.
本文通过全合成证实了抗生素支链霉素和基德洛霉素的复杂而有趣的结构。对合成产物的仔细滴定表明,kibdelomycin 是 ammycolamicin 的盐形式。该合成采用高度收敛的策略,为进一步研究此类抗生素的 SAR 提供了模块化方法。
Boronic Acids as Phase-Transfer Reagents for Fischer Glycosidations in Low-Polarity Solvents
作者:Sanjay Manhas、Mark S. Taylor
DOI:10.1021/acs.joc.7b01880
日期:2017.11.3
Protocols employing phenylboronic acid as a phase-transfer reagent for Fischer glycosidations in low-polarity organic solvents are described. In addition to providing rate acceleration, the formation of a substrate-derived boronic ester alters the course of the reaction by selective promotion of a furanoside- or pyranoside-selective pathway. Computational modeling of the relative energies of the glycoside-derived
Effective Organotin-Mediated Regioselective Functionalization of Unprotected Carbohydrates
作者:Yixuan Zhou、Kuo-Shiang Liao、Tzu-Yin Chen、Yves S. Y. Hsieh、Chi-Huey Wong
DOI:10.1021/acs.joc.3c00397
日期:2023.6.2
carbohydrates. The counteranion of tetrabutylammonium ion with a weak coordination ability plays a crucial role in the improved regioselective reactions. A convenient access to the intermediates of synthetic value is also demonstrated in the organotin-mediated regioselective tosylation of unprotected carbohydrates, followed by the nucleophilic inversion reaction to give sulfur-containing and azide-modified
A new strategy for diversity-oriented direct glycosylation of bioactive small molecules was developed. This reaction features (-)-beta-pinene as acid scavenger and work with glycosyl iodides under mild conditions. With the aid of RP-HPLC and chiral SFC separation techniques, the new direct glycosylation proved effective at gram scale on bioactive small molecules including AZD6244, podophyllotoxin, paclitaxel, and docetaxel. Interesting glycoside derivatives were efficiently created with good yields and 1,2-cis selectivity.