Asymmetric [3,3]- and [1,3]-sigmatropic rearrangements of gamma-allyloxy vinylogous urethanes.
Vinylogous urethanes derived from condensation of prolinol or prolinol tert-butyldimethylsilyl ether with 4-allyloxyketoester were found to undergo a thermal [3,3]-sigmatropic rearrangement, providing compounds with N-substituted quaternary carbon centers. Cyclizations (subsequently or in situ) of the rearranged products generated hexahydro-3,4-dioxa-8a-aza-as-indacen-2-ones. Various terminally substituted allyloxy ketoesters and arylmethoxy ketoesters were found to generate tricyclic compounds via [1,3]-sigmatropic rearrangement. Finally, tricyclic lactones were transformed successfully into lactams.
Li
Yu-Jang
YJ
Department of Applied Chemistry, National Chiayi University, 300 University Road, Chiayi City, 600 Taiwan. yjli@mail.ncyu.edu.tw
Chang
Yuan-Kang
YK
Ho
Guo-Ming
GM
Huang
Hua-Ming
HM