Synthesis and reactivity of hexahydropyrroloquinolines

Formal [4+2] cycloaddition of cyclic enamides with imines derived from arom atic amines gave the 4-arylhexahydropyrroloquinoline skeleton in one step a s mixtures of diastereoisomers. Aromatic imines derived from formaldehyde a nd methylglyoxalate also participated in this chemistry, with the latter fa vouring formation of the endo-cycloadduct. The cycloadducts derived from me thylglyoxalate were unstable and fragmented to give highly substituted quin olines under both neutral and basic conditions. Imines derived from 3-cyano acrolein also underwent cycloaddition and gave an advanced potential precur sor to martinellic acid, albeit with poor diastereoselectivity. (C) 2001 El sevier Science Ltd. All rights reserved.