Pyrrolizidine alkaloids. The synthesis and absolute configuration of all stereoisomers of monocrotalic acid.

T Matsumoto, M Takahashi, Y Kashihara

Index: Matsumoto,T. et al. Bulletin of the Chemical Society of Japan, 1979 , vol. 52, p. 3329 - 3336

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Citation Number: 11

Abstract

All stereoisomers (3a, b–6a, b) of monocrotalic acid have been synthesized. Methylation of (±)-cis-2, 3, 4-trimethyl-2-pentenedioic acid with diazomethane followed by cis-hydroxylation with potassium permanganate afforded two epimeric γ-lactone esters in a ratio of ca. 1: 5. These esters were then hydrolyzed with dilute hydrochloric acid to the corresponding acids,(±)-3 and racemic monocrotalic acid (4). Optical resolution of (±)-3 with brucine ...