Highly stereoselective syntheses of spiroacetal enol ethers, (E)- and (Z)-methoxycarbonylmethylene-1, 6-dioxaspiro[4.5]decanes
作者:Hiroaki Toshima、Hisateru Aramaki、Furumoto Yoshinori、Shintaro Inamura、Akitami Ichihara
DOI:10.1016/s0040-4020(98)00241-5
日期:1998.5
(E)- and (Z)-2-methoxycarbonylmethylene-1,6-dioxaspiro[4.5]decanes have been synthesized from an acyclic keto alcohol possessing an alkynoate part via intramolecular conjugate addition. Under thermodynamically controlled conditions using t-BuOK in THF, the (E)-isomer could be obtained in 52:1 ratio. When a catalytic amount of Pd(OAc)2 was used in benzene, the (Z)-isomer could be obtained in 95:1 ratio
(E)-和(Z)-2-甲氧基羰基亚甲基-1,6-二氧杂螺[4.5]癸烷是通过分子内共轭加成反应从具有炔烃部分的无环酮醇合成的。在热力学控制的条件下,使用t- BuOK在THF中的溶液,可以以52:1的比例获得(E)-异构体。当在苯中使用催化量的Pd(OAc)2时,可以以95:1的比例获得(Z)-异构体。