Stereocontrolled chemical glycosylation remains a major challenge despite vast efforts reported over many decades and so far still mainly relies on trial and error. Now it is shown that the relative reactivity value (RRV) of thioglycosides is an indicator for revealing stereoselectivities according to four types of acceptors. Mechanistic studies show that the reaction is dominated by two distinct intermediates:
Highly Stereoselective Glycosyl-Chloride-Mediated Synthesis of 2-Deoxyglucosides
作者:Ved Prakash Verma、Cheng-Chung Wang
DOI:10.1002/chem.201203418
日期:2013.1.14
Cl intermediates: The glycosylation of per-O-benzylated 2-deoxy- and 2,6-dideoxythioglycosides, promoted by the combination of para-toluenesulfenyl chloride (p-TolSCl) and silver triflate (AgOTf), furnished the products in high yields and high stereoselectivity. The glycosyl chloride was the intermediate (see scheme).