nucleophilic than corresponding phosphoranes. The sugar enones are reduced to appropriate allylic alcohols with zinc borohydride; the stereoselectivity of this process is >97:3 (with the D-glycero isomer predominating) when the carbonyl group is placed at the α-position to the sugar ring. CD spectroscopy was used for the determination of the configuration of higher sugar allylic alcohols.
摘要糖衍生的
膦酸酯[Sug-C(O)
CH2P(O)(OMe)2]与糖醛(Sug'-CHO)的反应提供了通式为Sug-C(O)CH = CH-Sug的高级烯酮具有双键的反式构型。
膦酸酯方法优于先前使用的膦烷方法[Sug-C(O)CH = PPh3 + Sug'-CHO],因为糖
膦酸酯可以以更高的产率制备并且比相应的膦烷亲核得多。用
硼氢化锌将糖烯酮还原为合适的
烯丙醇;当羰基位于糖环的α-位置时,此过程的立体选择性> 97:3(D-
甘油异构体占主导)。CD光谱法用于确定高级糖烯丙基醇的构型。