Claisen orthoester rearrangement in the direct preparation of Z-isositsirikine and Z-geissoschizine derivatives possessing the right oxidation state at C-17
作者:Mauri Lounasmaa、Pirjo Hanhinen、Reija Jokela
DOI:10.1016/0040-4020(95)00477-p
日期:1995.7
In the cases of trialkyl 3,3-dialkoxyorthopropionates [triethyl 3,3-diethoxyorthopropionate 14b (or 3,3-diethoxymethylketene diethylacetal 20b) and trimethyl 3,3-dimethoxyorthopropionate 14 a (or 3,3-dimethoxymethylketene dimethylacetal 20a)], the intermediate ketene acetals 25a,b do not rearrange according to the Claisen mechanism to form compounds 26a,b and/or 27a,b possessing two RO-functions at
利用烯丙醇1(或2)和3-甲氧基ortbopropionate三甲基丙烯酸13a进行的Claisen原酸酯重排导致Z-异三烷衍生物21a-22a(或23a-24a)在C-17处具有一个RO功能。在三烷基3,3- dialkoxyorthopropionates的情况下[三乙基3,3- diethoxyorthopropionate 14B(或3,3-二乙diethoxymethylketene 20B)和三甲基3,3- dimethoxyorthopropionate 14(或3,3-二甲基缩醛dimethoxymethylketene 20A)],则中间乙烯酮缩醛25a,b不会根据克莱森机理进行重排以形成化合物26a,b和/或27a,b在C-17上具有两个RO功能。描述了中间体原酸酯的合成,即3-甲氧基原丙酸三甲酯13a,3,3-二甲氧基原丙酸三甲酯14a,反式-3-甲氧基原丙酸三甲酯2