A Short and Practical Synthesis of (+)-Pseudoconhydrine and (+)-N-Methylpseudoconhydrine via Osmium Catalyzed Asymmetric Dihydroxylation

Isolation, structure elucidation, and synthesis of dehydro-4-rnethoxycyclobrassinin (I), a turnip phytoalexin possessing a novel heterocyclic system, are described.Phytoalexins are low molecular weight antimicrobial compounds synthesized de novo by plants after their exposure to micro-organisms.? These abnormal secondary metabolites are not usually detected in healthy plant tissues and their accumulation is considered to be one of the important disease resistance mechanisms.3In a continuation of our studies on vegetable phytoalexins,4 we have reported several indolic phytoalexins from crucifers such as Chinese cabbage,s cabbage.=and radish.'These studies indicated that crucifers are a rich source of novel bioactive heterocyclic compounds.