The tandem cycloaddition chemistry of nitroalkenes. A novel synthesis of (-)-hastanecine

Article abstract of DOI:10.1021/jo00098a027

A short and efficient asymmetric synthesis of the pyrrolizidine necine base (-)-hastanecine is described. The key reaction in the synthesis is a sequential inter [4 + 2]/inter [3 + 2] cycloaddition. The Lewis acid promoted [4 + 2] cycloaddition between 2-