Formation of 2-Cyano-2-siloxyvinylallenes via Cyanide-Induced Brook Rearrangement in γ-Bromo-α,β,γ,δ-unsaturated Acylsilanes
作者:Masafumi Ando、Michiko Sasaki、Izumi Miyashita、Kei Takeda
DOI:10.1021/jo502323v
日期:2015.1.2
using n-Bu4NBr afforded 2-cyano-2-siloxyvinylallenes via a tandem process that involves a nucleophilic attack of a cyanide ion and a Brook rearrangement induced conjugate vinylic 1,4-elimination. Use of a chiral cyanide ion source, derived from KCN and quaternary ammonium bromide derived from cinchona alkaloids, provided nonracemic allene derivatives. Based on this result and the reaction using a chiral
γ-溴-α,β,γ,δ-不饱和酰基硅烷与KCN在相转移催化剂条件下使用n -Bu 4 NBr的反应通过串联过程得到2-氰基-2-甲硅烷基乙烯基烯,涉及到氰化物的亲核攻击离子和布鲁克重排诱导共轭乙烯基1,4-消除。使用衍生自KCN的手性氰化物离子源和衍生自金鸡纳生物碱的季铵溴化物,可提供非外消旋的烯丙基衍生物。根据此结果和使用手性氢离子源的反应,我们提出了一条反应途径,其中布鲁克重排介导的乙烯基共轭1,4-消除发生在C-Br键和C-Si键之间的顺式排列中。硅酸盐中间体。