4-Thiazolidinones in Heterocyclic Synthesis: Synthesis of Novel Enaminones Azolopyrimidines and 2-Arylimino-5-arylidene-4-thiazolidinones

摘要

The 4-thiazolidinones >3a–d were used as a key intermediates for the synthesis of 2-arylimino-5-arylidene-4-thiazolidinones derivatives >7a–p via nucleophilic addition reactions with the arylidene malononitrile. Moreover the 4-thiazolidinones >3a and >3c condensed with the DMF-DMA to form the corresponding enamines >8 and >9 depending on the reaction conditions. Otherwise the 4-thiazolidinone >3b reacts regioselectively with DMF-DMA to afford the enaminones >10 and >11, respectively. The latter reacts with many heterocyclic amines affording polyfunctionally substituted fused pyrimidine derivatives >13–18. The enamine >8b was also reacted with the 3-amino-1,2,4-triazole to afford the acyclic product >19, which could not be further cyclized to the corresponding tricyclic system >20. Moreover the 4-thiazolidinone >3c reacted with the benzenediazonium chloride to afford the arylhydrazones >12. The X-ray single crystal technique was employed in this study for structure elucidation and Z/E potential isomerism configuration determination. The X-ray crystallographic analyses of eight products could be obtained, thus establishing with certainty the structures proposed in this work.