Thermal Rearrangement of 7-Methylbicyclo[3.2.0]hept-2-ene: An Experimental Probe of the Extent of Orbital Symmetry Control in the [1,3] Sigmatropic Rearrangement
作者:Jared D. Bender、Phyllis A. Leber、Ruel R. Lirio、Randall S. Smith
DOI:10.1021/jo9918899
日期:2000.8.1
gas-phase thermal rearrangement of exo-7-methylbicyclo[3.2.0]hept-2-ene yields almost exclusively 5-methylnorbornene products. Inversion (i) of configuration dominates this [1,3] sigmatropic shift although some retention (r) is also observed. Because the [1,3] migration can only occur suprafacially (s) in this geometrically constrained system, the si/sr ratio of 7 observed for the migration of C7 in
exo-7-甲基双环[3.2.0]庚-2-烯的气相热重排几乎只能生成5-甲基降冰片烯产品。构型倒置(i)主导了[1,3]σ偏移,尽管也观察到了一些保留(r)。因为[1,3]迁移只能在表面上发生在此几何约束系统中,所以在exo-7-甲基双环[3.2.0]庚-2-烯中C7迁移时观察到的si / sr比为7。指出轨道对称性规则对于碳的[1,3]σ迁移具有一定的容许性。