Asymmetric synthesis. XX. Preparation of a novel spiropiperidine system by the CN(R,S) method

A novel spiropiperidine system I i.e. an aza structural analog of histrionicotoxin was constructed from 2-cyano-6-phenyloxazolopiperidine synthon II. The suitable quaternary carbon was created by alkylation at the position alpha to the nitrile followed by transformation of the nitrile group into a primary amine. Final aminoreductive cyclization gave the spiro system. [on SciFinder (R)]