title: Asymmetric [3,3]- and [1,3]-sigmatropic rearrangements of gamma-allyloxy vinylogous urethanes.
abstract: 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.
authors.affiliation: Department of Applied Chemistry, National Chiayi University, 300 University Road, Chiayi City, 600 Taiwan. yjli@mail.ncyu.edu.tw
authors.forename: Yu-Jang
authors.initials: YJ
authors.lastname: Li
authors.forename: Yuan-Kang
authors.initials: YK
authors.lastname: Chang
authors.forename: Guo-Ming
authors.initials: GM
authors.lastname: Ho
authors.forename: Hua-Ming
authors.initials: HM
authors.lastname: Huang