The first stereoselective one-pot synthesis of the icosasaccharide motif of EPS-1A glycanfrom Cordyceps sinensis has been achieved. The synthetic approach highlights the following features: (1) merging reagent modulation and remote anchimeric assistance α-glycosylation strategy for the highly stereoselective formation of five and ten continuous 1,2-cis glucosidic bonds; (2) the strategic employment
CPS K43, K47 and K88 repeating units have been accomplished via a new α-glycosylation method with GlcN3 as donors, which features: 1) mild reaction conditions, 2) good to high yields, 3) excellent stereoselectivities. The synthetic route also highlights an orthogonal one-pot coupling strategy on the basis of glycosyl ortho-(1-phenylvinyl)benzoates for stereoselective constructions of both 1,2-trans
An efficient and recyclable catalyst for the cleavage of tert-butyldiphenylsilyl ethers
作者:Shiqiang Yan、Ning Ding、Wei Zhang、Peng Wang、Yingxia Li、Ming Li
DOI:10.1016/j.carres.2012.02.021
日期:2012.6
An efficient, chemoselective, and environment-friendly method for the deprotection of tert-butyldiphenylsilyl ethers mediated by triflic acid supported on silica gel is reported. A wide range of tert-butyldiphenylsilyl ethers derived from carbohydrate and saponin residues can be smoothly cleaved in the presence of various types of other protecting groups in good to excellent yields in acetonitrile. This heterogeneous reaction does not require aqueous workup, and the supported catalyst can be readily recycled. (C) 2012 Elsevier Ltd. All rights reserved.