5- Methyl-6-phenylimidazo thiazole

YZ1367). On treatment of 6-/ -chlorophenyl-3-methyl-5-nitroso-imi-dazo[2,l-6]thiazole with dilute hydrochloric acid in dioxane at rt a ring transformation occurs [92JCS(CC)1394], Vilsmeyer-Haack reaction of 3-methy -6-phenylimidazo[2,l-6]thiazole (70, R = = H, R = Me, R" =... 

Reactions of imidazo[2,l-fe]benzothiazoles and imidazo [2,l-b]thiazoles with dibenzoylacetylene (82BCJ200) proceed similarly. Potts and Kane-masa (79JOC3803) found that DM AD and dibenzoylacetylene react with anhydro-3-hydroxy-7-methyl-2-phenylimidazo[2,l-f>]thiazolium hydroxide to give 86, although in poor yield. Probably adducts of type 85 are intermediates. 

Methyl-6-phenylimidazo[2,1 -/ ]thiazole (55a) has been reported to give the 4-nitrosophenyl product, but 2,5-dimethyl-6-phenylimidazo[2,1 -b]thia-zole is reported not to react with nitrous acid, so the product of the reaction is most likely to be the 3-substituted compound (61LA145). 

---