Stereocontrolled thio-Claisen rearrangement of S-allylic ketene aminothioacetals by an hydroxysubstituted adjacent stereogenic centre
作者:Pierre Beslin、Bruno Lelong
DOI:10.1016/s0040-4020(97)10178-8
日期:1997.12
(Z)-S-allylic ketene aminothioacetals were prepared from N,N-Dimethyl β-hydroxythioamides 2–8 by deprotonation with LDA (2 eq.) at −78°C followed by S-alkylation with allylic bromide. Rearrangement of these compounds occured easily at room temperature affording major syn N,N-dimethyl β-hydroxy α-allylic thioamides 9–21 with a syn/anti ratio of to . The syn configuration of the major diastereoisomer
(Z)-S-烯丙基烯酮氨基硫缩醛是由N,N-二甲基β-羟基硫代酰胺2-8通过在-78°C下用LDA(2当量)去质子化,然后用烯丙基溴进行S-烷基化而制得的。这些化合物在室温下很容易发生重排,从而得到主要的N,N-二甲基β-羟基α-烯丙基硫酰胺9–21合成,反式/反式比为。主要的非对映异构体的顺式构型已通过顺式合成的硫代酰胺9和11证实。通过经验的13 C NMR规则确认了结构分配。所提出的过渡状态模型很好地支持了观测到的归纳。