Abstract
We have developed a facile oxidative approach for the synthesis of C-4 functionalized 2-oxo-2H-benzo[h]chromenes. The required precursors, 4-(methylthio)-2-oxo-5,6-dihydro-benzo[h]chromenes were synthesized by reaction of 1-tetralones and 2-cyano-3,3-bis(methylthio)acrylate under basic conditions, which can be further aminated with different secondary amines in refluxing ethanol. We have reported the NBS and AIBN mediated oxidation of 5,6-dihydro-benzo[h]chromenes to afford 4-(substituted)-2-oxo-benzo[h]chromenes. The scope of dehydrohalogenation was further extended for the synthesis of thiophene-fused chromenes. Reactivity of synthesized 4-(substituted)-2-oxo-benzo[h]chromenes was also explored with C- and S-nucleophiles.