Peracetylated α-glycobiosyl bromides 1-5 derived from commercially available disaccharides, were transformed with complete anomeric stereocontrol into phenyl 1,2-trans-1-thio-β-D-glycobiosides 6-10 by nucleophilic displacement under phase transfer catalyzed glycosidation in 77-92% yields. The reaction proceed rapidly for most bromides in dichloromethane, but failed under similar conditions, to provide complete conversion of the melibiosyl bromide 4 into the S-phenyl thioglycoside 9. Nevertheless, the reaction gave good results when performed in toluene or ethyl acetate.
商业上可获得的二糖衍生的过乙酰化α-糖基
溴化物1-5,在相转移催化的糖苷化条件下通过亲核取代反应,以77-92%的收率完全立体选择性地转化为苯基1,2-反式-1-
硫代-β-D-糖苷6-10。对于大多数
溴化物,反应在
二氯甲烷中能快速进行,但在相似条件下,无法将美力糖基
溴化物4完全转化为S-苯基
硫代糖苷9。然而,当在
甲苯或
乙酸乙酯中进行反应时,能获得良好的结果。