Crystalline 2,3:4,5-di-O-isopropylidene-dl-arabinose diethyl dithioacetal: Some reactions of acetal derivatives of arabinose
作者:Derek Horton、Oscar Varela
DOI:10.1016/0008-6215(84)85038-7
日期:1984.12
Acetonation of the diethyl dithioacetals of D- and L-arabinose gives the corresponding 2,3:4,5-diisopropylidene acetals (2a and 2b) as oils having [alpha]D +82 and -81 degrees, respectively; in admixture, the enantiomers form a well crystallized racemate, m.p. 43-45 degrees. The initial product of acetonation is the 4,5-monoisopropylidene acetal. Demercaptalation of 2a with mercury(II) chloride-cadmium
D-和L-阿拉伯糖的二乙基二硫缩醛的乙酰化分别得到相应的2,3:4,5-二异亚丙基缩醛(2a和2b),其为αD+82和-81度的油;在混合物中,对映异构体形成结晶良好的外消旋体,mp 43-45度。丙酮化的初始产物是4,5-单异亚丙基乙缩醛。用氯化汞(II)-碳酸镉对2a脱巯基化反应可高产率获得2,3:4,5-二-O-异亚丙基-醛-D-阿拉伯糖(5),但文献报道的方法使用氯化汞(II)-氧化汞(II)可提供5和1,2:3,4-二-O-异亚丙基-β-D-阿拉伯吡喃葡萄糖(6)的混合物。痕量的酸可将醛衍生物5完全完全转化为环状二缩醛6。