Steric course of proton removal during the cyclisation of β-cyclopiazonic acid in Penicillium cyclopium

Abstract

Incorporation of (3R)- and (3S)-[3-3H,3-14C] tryptophan into α-cyclopiazonic acid in Pencillium cyclopium Westling proceeds with loss of pro-S-tritium showing that, in the final cyclisation step, formation of the new C–C bond occurs from the opposite side of the molecule to proton removal.