A direct intramolecular asymmetric catalytic aldol cyclodehydration of meso-3,4-disubstituted-1,6-dialdehydes

The intramolecular asymmetric catalytic aldol cyclodehydration of 1,6-dialdehydes to the corresponding cyclopentene carbaldehydes was accomplished for the first time on the cases of meso-3,4-disubstituted hexanedials. It was found that the presence of a hydroxyl group in the catalyst's molecule seems to be crucial to reach stereocontrol. The chiral centre, bearing the carboxylate functionality, in hydroxy amino acids controls the stereochemistry of the final product. In the case of amino alcohols, where carboxylate functionality does not exist, the configuration of the carbon, connected with the hydroxyl group, seems to be the key one. Additionally, it was observed that chiral phosphines and phosphites are effective catalysts for this cycloclehydration but without inducing stereocontrol. (C) 2004 Elsevier Ltd. All rights reserved.