Highly beta-selective and direct formation of 2-O-glycosylated glucosides by ring restriction into twist-boat

作者：Okada Yasunori^*; Nagata Osamu; Taira Miyoko; Yamada Hidetoshi

来源：Organic Letters, 2007, 9(15): 2755-2758.

DOI：10.1021/ol070720b

Three disaccharide donors, ethyl 2- O- ( 2,3,4- tris- O- tert- butyldimethylsilyl-beta- (D)- xylopyranosyl)- 3,4,6- tris- O- tert- butyldimethylsilyl- 1- thio-beta- (D)- glucopyranoside, ethyl 2- O- ( 2,3,4- tris- O- tert- butyldimethylsilyl- alpha- (L)- rhamnopyranosyl)- 3,4,6- tris- O- tert- butyldimethylsilyl- 1- thio-beta- (D)- glucopyranoside, and ethyl 2- O( 2,3,4,6- tetrakis- O- tert- butyldimethylsilyl-beta- (D)- glucopyranosyl)- 3,4,6- tris- O- tert- butyldimethylsilyl- 1- thio-(beta)- (D)- glucopyranoside, produced a highly beta- selective glycosidation up to alpha/beta = 2/ 98 using MeOTf as the activator and 2,6- lutidine as an additive. The ring conformations of the glucose part in these disaccharide donors were all restricted to S-3(1), and the conformation would lead to the stereoselectivity.

• 出版日期2007-7-19