Nucleophilic Addition Reaction to the Iminium Salts Generated from Pipecolic Acid Derivatives and Application to the Synthesis of Bicyclic Compounds

摘要

Nucleophilic addition of Grignard reagents to the iminium salts generated by the oxidation of cyclic amino ketene silyl acetals derived from pipecolic acid gave alpha-quaternary amino ester derivatives. Bicyclic compounds were prepared from N-allylated and homoallylated derivatives with vinylaion, allylation, or homoallylation followed by ring-closing metathesis. Application of this method to the synthesis of (+/-)-S22178, a potent 5-HT1A agonist, was also described.