Enantioselective Syntheses of 2-Alkyl- and 2,6-Dialkylpiperidine Alkaloids: Preparations of the Hydrochlorides of (−)-Coniine, (−)-Solenopsin A, and (−)-Dihydropinidine

Abstract
Sequences of lithiation−substitution, enantioselective hydrogenation, and diastereoselective lithiation−substitution provide efficient highly enantioselective syntheses of 2-substituted and cis and trans 2,6-disubstituted piperidines. The methodology is demonstrated by syntheses of (−)-coniine, (−)-solenopsin A, and (−)-dihydropinidine as their hydrochlorides.