Ring Transformations if Oxazoles and Their Benzo Analogues. New Synthetic Route for 2H-Amidazo[2,1-b][1,3,4]thiadiazine and N-Heteroaryl-o-aminophenol

Abstract

Ring transformations of certain fmctionalized oxazoles and their benzo analogues were studied.The a-(oxazol-2-ylthio) ketones g, b, 5, and e gave 2H-imidazo[Z,l-b][1,3,4]thiadiazines (&, b, 5, and 5) on treatment with hydrazine hydrate in acetic acid.Similar treatment of ketones g and f-h resulted in the formation of the complex mixtures.The a-(benzoxazol-2-ylthio) ketones and b reacted with amnonium acetate in acetic acid to give 2-(2-hydroxypheny1amino)thiazoles 9 and b in quantitative yields.With hydrazine, 5a afforded thiazoline derivative Iwhile %-provided 1,3,4-thiadiazine deriv--