The total syntheses of the necine base (+/-)-platynecine and of a new indolizidine were accomplished. Both syntheses feature a [2+2] cycloaddition of a common endocyclic enecarbamate with alkylketenes in a new and concise strategy for the construction of pyrrolizidine and indolizidine skeleta. These syntheses were carried out in four steps in good overall yields.362951095112