A SHORT ACCESS TO CHIRAL NON-RACEMIC OXA- AND AZAHETEROCYCLES BY CROSS-METATHESIS AND PD-CATALYZED CYCLIZATION SEQUENCE

摘要

A concise synthesis of chiral non-racemic 2-(3-benzoyloxyprop-1-enyl)tetrahydrofuran (5a), tetrahydropyran (5b), and piperidine (8) is described. Cross-metathesis of optically pure (S)-1-O-benzoyl-3-butene-1,2-diol (2) with protected 4-pentenol, 5-hexenol, and 5-hexenylamine gave the corresponding allyl alcohols (3a), (3b), and (7) in one step, respectively. PdCl2(MeCN)2 catalyzed cyclization of 4a, 4b, and 7 afforded 5a, 5b, and 8 in excellent yields with high enantiomeric purity.