Enantioselective construction of nitrogen-substituted quaternary carbon centers adjacent to the carbonyl group in the cyclohexane ring: first asymmetric synthesis of anesthetic (S)-ketamine with high selectivity
作者:Reiko Yokoyama、Satoshi Matsumoto、Satoshi Nomura、Takafumi Higaki、Takeshi Yokoyama、Syun-ichi Kiyooka
DOI:10.1016/j.tet.2009.05.004
日期:2009.7
amino ketone 12. However, the reaction of 2-chlorophenyllithium did not work in which this route was unavailable for the synthesis of 1. Then, an alternative strategy directed toward 1, starting with a compound having 2-chlorophenyl groups in advance, was designed in which the chiral quaternary carbon center bearing a nitrogen atom in the ring is created by the enantioselective reduction of the atropisomeric
关于麻醉剂(S)-氯胺酮1的不对称合成,进行了与环己烷环中的羰基相邻的氮取代的季碳中心的对映选择性结构。苯基锂与在α-羰基官能团上带有手性助剂的α-酮肟-乙缩醛9的非对映选择性亲核1,2-加成反应,生成的苄氧基胺11主要产率为83%,de为82%,转化为相应的氨基酮12。然而,2-氯苯基锂的反应不起作用,其中该路线不可用于合成1。然后,针对1的替代策略从预先具有2-氯苯基基团的化合物开始,设计了其中通过在对映异构体中间酮18的对映选择性还原和将氰酸烯丙基酯连续转化为对映体而形成在环中带有氮原子的手性季碳中心。异氰酸酯重排,具有完整的1,3-手性转移。根据该策略,通过短路径完成了具有极佳选择性(> 99%ee)的1的第一个不对称合成。