摘要:
A novel synthesis of 2,6-diaryl-4H-thiopyran-4-ones has been developed. The title compounds were prepared by two sequential thio-Claisen condensations of a dialkyl ketone and two dithioesters. The intermediate beta-thioxo ketone from the first condensation was converted to the corresponding beta-(methylthio) enone for both protection and reactivity purposes. Facile addition-elimination of the methylthio moiety by a beta-thioxo ketone enolate generated in the second thio-Claisen condensation afforded the desired heterocycle. This new method is rapid and simple with the only requirement being moderate substituent alkaline stability.