An Approach to a Chiral Cycloalkanone-Mediated Asymmetric Epoxidation of Stilbene with Oxone.
作者:Koichiro MATSUMOTO、Kiyoshi TOMIOKA
DOI:10.1248/cpb.49.1653
日期:——
Chiral and C2-symmetric seven-membered cycloalkanones 2-6 bearing 1,2-diphenylethane-1,2-diamine and cyclohexane-1,2-diamine backbones were synthesized and evaluated their asymmetry inductive behaviours in an asymmetric epoxidation of stilbene with Oxone®. Although the reaction of the ketones 2 and 3 of a 1,2-diphenylethane-1,2-diamine backbone gave stilbene oxide in trace to 31% yield, those of the ketones 4-6 of a cyclohexane-1,2-diamine backbone gave the epoxide in satisfactorily high yield up to 98%. It is noteworthy that both reactions with use of stoichiometric and substoichiometric amounts of a ketone 4 gave the epoxide in the essentially same enantioselectivity, 17 and 18%. Eleven-membered cyclic ketones 7 and 8 bearing a binaphthalene backbone were also synthesized and examined their behaviours, while the enantioselectivity turned out to be marginal.
合成了带有 1,2-二苯基乙烷-1,2-二胺和环己烷-1,2-二胺主链的手性和 C2 对称七元环烷酮 2-6,并评估了它们在 Oxone® 茋不对称环氧化反应中的不对称诱导行为。虽然 1,2-二苯基乙烷-1,2-二胺主链的酮 2 和 3 的反应产生了二苯乙烯氧化物,收率高达 31%,但环己烷-1,2-二胺主链的酮 4-6 的反应生成了二苯乙烯氧化物。环氧化物的产率令人满意,高达 98%。值得注意的是,使用化学计量和亚化学计量量的酮 4 的两个反应都以基本相同的对映选择性(17% 和 18%)生成环氧化物。还合成了带有联萘主链的十一元环酮 7 和 8 并检查了它们的行为,但对映选择性却很有限。