1-Lithiated O-vinyl carbamates add with high induced diastereoselectivity onto enantiomerically pure cycloalk-1-enyl (1-dibenzylamino)alkyl ketones. Subsequent O-carbamoyl migration, followed by a torquoselective, antarafacial 4Ï ring closure, leads to homochiral 2-substituted bicyclo[n.3.0]alk-1-ene-2-ones.
1-
锂化O-
乙烯基氨基甲酸酯以高诱导的非对映选择性与对映体纯的环烯烃(1-二苯基
氨基)烷基酮发生反应。随后,O-
氨基甲酰迁移,再经过扭转选择性的反面4π环闭合,生成同手性的2-取代双环[n.3.0]烷-1-烯-2-酮。