Achiral 2-Hydroxy Protecting Group for the Stereocontrolled Synthesis of 1,2-cis-伪-Glycosides by Six-Ring Neighboring Group Participation

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• 作者：Govind P. Singh ; Andrew J. A. Watson ; Antony J. Fairbanks
• 刊名：Organic Letters
• 出版年：2015
• 出版时间：September 4, 2015
• 年：2015
• 卷：17
• 期：17
• 页码：4376-4379
• 全文大小：394K
• ISSN：1523-7052

文摘

Glycosylation of a fully armed donor bearing a 2-O-(trimethoxybenzenethiol) ethyl ether protecting group is completely 伪-selective with a range of carbohydrate alcohol acceptors. Low-temperature NMR studies confirm the intermediacy of cyclic sulfonium ion intermediates arising from six-membered 尾-sulfonium ring neighboring group participation. Selective protecting group removal is achieved in high yield in a single operation by S-methylation and base-induced 尾-elimination.