Sequential Directed Epoxydation-Acidolysis from Glycals with MCPBA. A Flexible Approach to Protected Glycosyl Donors

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• 作者：Irene Mar铆n ; Javier Castilla ; M. Isabel Matheu ; Yolanda D铆az ; Sergio Castill贸n
• 刊名：Journal of Organic Chemistry
• 出版年：2011
• 出版时间：December 2, 2011
• 年：2011
• 卷：76
• 期：23
• 页码：9622-9629
• 全文大小：951K
• 年卷期：v.76,no.23(December 2, 2011)
• ISSN：1520-6904

文摘

4,6-Di-O-protected glucal and allal derivatives react with MCPBA to afford manno- and allo-1-O-m-chlorobenzoate derivatives, respectively, as a result of a syn epoxidation directed by the allylic hydroxyl group, and consecutive ring-opening by m-ClBzOH. When glucal and allal derivatives are fully protected, initial epoxidation proceeds mainly anti to the allylic group to give, after ring-opening, the corresponding pyranosyl chlorobenzoates. Stereoselectivity in the reaction of fully protected galactal derivatives was complete, although only a moderate increase in the syn epoxidation product was observed in 4,6- and 3,4-di-O-protected derivatives. 1-O-m-Chlorobenzoate 18 was selectively protected and activated as donor in the synthesis of disaccharide 21.