Neighbouring group participation vs. addition to oxacarbenium ions: studies on the synthesis of mycobacterial oligosaccharides
作者:Susanne A. Stalford、Colin A. Kilner、Andrew G. Leach、W. Bruce Turnbull
DOI:10.1039/b914417j
日期:——
methylsulfide group in the product. Model reactions indicated that the bicyclic intermediate would also act as a participating group to direct the acceptor alcohol to the lower α-face of the sugar. While the key sulfonium intermediate could be detected in the reaction mixture, the glycosylation reaction proceeded with moderate stereoselectivity, apparently via an SN1-type mechanism. Density functional