Preparations of 5-alkylmethylidene-3-carboxymethylrhodanine derivatives and their aldose reductase inhibitory activity.

Abstract
Reactions of 3-carboxymethylrhodanine (1) with aldehydes (2a-u) afforded stereoselectively the 5-monoalkylmethylidene-3-carboxymethylrhodanines (3a-u). The configuration of the 5-monoalkylmethylidene-3-carboxymethylrhodanine (3k) were examined by X-ray structure analysis and confirmed to be Z-configuration. The stereoselective reaction path was discussed. Several 5-diakylmethylidene-3-carboxymethylrhodanines (15a-f) and alkylamino derivatives of 3-carboxymethylrhodanines (18a-o) were also prepared. These products were evaluated for aldose reductase-inhibitory potency and half of then exhibited valuable inhibitory potency.