Stereo- and regiocontrolled syntheses of exomethylenic cyclohexane β-amino acid derivatives

Abstract

Cyclohexane analogues of the antifungal icofungipen [(1R,2S)-2-amino-4-methylenecy clopentanecarboxylic acid] were selectively synthesized from unsaturated bicyclic β-lactams by transformation of the ring olefinic bond through three different regio- and stereocontrolled hydroxylation techniques, followed by hydroxy group oxidation and oxo-methylene interconversion with a phosphorane. Starting from an enantiomerically pure bicyclic β-lactam obtained by enzymatic resolution of the racemic compound, an enantiodivergent procedure led to the preparation of both dextro- and levorotatory cyclohexane analogues of icofungipen.