A Facile and Chemoselective Synthesis of Novel Pyrimido[5, 4‐b][1, 4]thiazines by exo‐dig Iodocyclization Reactions. (19th September 2016) - Sharma, Rashmi
Abstract : The present manuscript involves the synthesis of 5‐prop‐2‐ynylsulfanyl‐pyrimidin‐4‐ones3a–i by [4 + 2] cycloaddition reactions of 1, 3‐diazabuta‐1, 3‐dienes1a–i with prop‐2‐ynyl‐sulfanyl ketene2 . These 5‐prop‐2‐ynylsulfanyl‐pyrimidin‐4‐ones3a–i were explored in iodocyclization for the synthesis of novel pyrimido[5, 4‐ b ][1, 4]thiazines4a–i in excellent yields. The iodocyclizations followed exo‐ dig ring‐closure cyclizations to yield 6–6 bicyclic fused pyrimidinones, while corresponding endo ‐dig ring‐closure iodoamination was not observed. Abstract :