(2R)- and (2S)-2,3-Epoxypropyl, (3R)- and (3S)-3,4-epoxybutyl and (4S)- 4,s-epoxypentyl B- Dglucopyranoside , together with the (3R)- and (3s)-3,4-epoxybutyl β- cellobiosides , have been prepared by condensation of a glycosyl bromide with the appropriate enantiomer of a chiral alcohol containing a diol protected as an isopropylidene acetal, and subsequent manipulation of the unmasked diol into the epoxide function. As well, in an improvement to the whole process, both diastereoisomers of the various epoxypropyl and epoxybutyl glycosides were available from just the one enantiomer of the alcohol by an alternative manipulation of the diol. Finally, precursors to 2,3-epoxy-4-hydroxybutyl β-D-glucosides and β- cellobiosides were prepared in high optical purity by Sharpless asymmetric epoxidation of the appropriate 4-hydroxybut-2-enyl glycosides.
(2R)-和(2S)-2,3-环氧丙基、(3R)-和(3S)-3,4-环氧丁基和(4S)-4,s-环氧戊基 B-吡喃葡萄糖苷,以及(3R)-和(3S)-3,4-环氧丁基 β-胞二糖苷、的制备方法是将溴化糖基与含有作为异亚丙基缩醛保护的二元醇的手性醇的适当对映体缩合,然后将未掩蔽的二元醇与环氧化物官能团结合。此外,对整个过程进行改进后,只需通过对二元醇进行另一种操作,就可以从醇的一种对映体中获得各种环氧丙基和环氧丁基苷的非对映异构体。最后,通过对适当的 4-羟基丁-2-烯基苷进行 Sharpless 不对称环氧化反应,制备出了高光学纯度的 2,3-环氧-4-羟基丁基 β-D 葡糖苷和 β-纤维二糖苷的前体。