Spiro[4,5]deca-2,7-diene-1,6-dione (2a) and spiro[5,5]undeca-2,8-diene-1,7-dione (2b) were prepared by a direct synthesis starting from diethyl malonate. The two-step 1,2-reductions (NaBH4/CeCl3) of the diones gave cis/trans-diols, which could be easily transformed into diacetates. Both diacetates were subjected to Pd(0)-catalyzed allylic alkylations, in which the relative stereochemistry was retained.
Spiro[4,5]deca-2,7-diene-1,6-dione(
2a)和spiro[5,5]undeca-2,8-diene-1,7-dione(
2b)通过从
乙酸二
乙酯开始的直接合成制备。二酮的两步1,2-还原(NaBH
4/CeCl
3)产生了
/二醇,可以轻松转化为二乙酸酯。两种二乙酸酯都经过Pd(0)催化的烯丙基烷基化反应,其中相对立体化学得以保留。