Asymmetric desymmetrization of a prochiral 1, 3-diol was established by diastereoselective C-O bond fission of the chiral α-sulfinyl acetal 6. Treatment of 6 with titanium tetrachloride afforded mainly 7a via an oxonium intermediate, while with lithium diisopropylamide 7b was selectively obtained via diastereoselective β-elimination followed by an olefin isomerization.
通过手性α-亚磺酰基
缩醛6的不对称解对称化作用,实现了对映选择性的C-O键断裂,进而实现了对非手性1,3
-二醇的对称性破缺。将6与
四氯化钛反应主要得到经氧鎓离子中间体生成的7a,而与
二异丙基氨锂反应则通过对映选择性的β-消除反应后进行烯烃异构化,选择性地获得了7b。