Stereoselective Synthesis of Spiro Bis-C,C-α-arylglycosides by Tandem Heck Type C-Glycosylation and Friedel–Crafts Cyclization

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• 作者：Yen-Bo Chen ; Shi-Hao Liu ; Min-Tsang Hsieh ; Chih-Shiang Chang ; Chun-Hung Lin ; Chen-Yin Chen ; Po-Yen Chen ; Hui-Chang Lin
• 刊名：Journal of Organic Chemistry
• 出版年：2016
• 出版时间：April 1, 2016
• 年：2016
• 卷：81
• 期：7
• 页码：3007-3016
• 全文大小：415K
• ISSN：1520-6904

文摘

Spiro bis-C,C-α-arylglycosides were synthesized in three steps in 78–85% overall yields starting from exo-glycals. The initial Heck type C-aryl addition of exo-glycals with arylboronic acids afforded α-aryl-β-substituted C-glycosides with exclusive α-stereoselectivity. Among the products, β-ethanal α-aryl C-glycosides further reacted with alkylthiol in the presence of InCl₃, followed by in situ Friedel–Crafts cyclization to yield the desirable final products. We proposed a mechanism to explain how the α-aryl group serves as a main determinant of the cyclization.