A CONVENIENT SYNTHESIS OF 9#-THIOXANTHEN-9-ONES AND THEIR AZA-ANALOGUES

摘要

-An efficient method for the preparation of 9H-thioxanthen-9-ones and their three aza-analogues has been developed. The reaction of (2-fluorophenyl)(2-halophenyl)methanones, derived from l-bromo-2-fluorobenzenes and 2-halobenzaldehydes by an easy two-step sequence, with Na2S-9H2O in DMF at 60 °C gives 9i/-thioxanthen-9-ones. This procedure can be applied to the synthesis of 5H-[l]benzofhiopyrano[2,3-b](or [2,3-c])pyridin-5-ones or 10H-[1]~-benzothiopyrano[3,2-c]pyridin-10-ones starting from 2-, 3-or 4-chloropyridines, respectively.