Synthetic Studies toward Gelsemine. 2. Preparation of the Tetracyclic Skeletal Part by Way of a Highly Stereospecific Intramolecular Reaction of a Silyl Enol Ether with an N-Acyliminium Ion

Article abstract of DOI:10.1021/jo00251a049

The tetracyclic skeletal part of the oxindole alkaloid gelsemine (1) was prepared from (E)-3,5-hexadien-1-ol in nine steps, including as the key step an unprecedented stereospecific cyclization reaction of a triisopropylsilyl enol ether with an N-acyliminium ion intermediate to give a tricyclic aldehyde (3 -> 4).