Tandem base-promoted ring-opening/Brook rearrangement/allylic alkylation of O-silyl cyanohydrins of beta-silyl-alpha,beta-epoxyaldehyde: scope and mechanism.
Metalated O-silyl cyanohydrins of beta-silyl-alpha,beta-epoxyaldehyde have been found to serve as functionalized homoenolate equivalents by a tandem sequence involving base-promoted ring opening of the epoxide, Brook rearrangement, and alkylation of the resulting allylic anion. On the basis of mechanistic studies involving competitive experiments using the diastereomeric cyanohydrins, we propose a reaction pathway involving a silicate intermediate 36 formed by a concerted process via an anti-opening of the epoxide followed by the formation of an O-Si bond.
Sasaki
Michiko
M
Department of Synthetic Organic Chemistry, Graduate School of Medical Sciences, Hiroshima University, 1-2-3 Kasumi, Minami-Ku, Hiroshima 734-8551, Japan.
Kawanishi
Eiji
E
Nakai
Yoshio
Y
Matsumoto
Tatsuya
T
Yamaguchi
Kentaro
K
Takeda
Kei
K