A Simple Route to New N(3)-Substituted 5-Aryl-2-(dialkylamino)-1,3-oxazolium Salts and N(1)-Substituted 4-Aryl-2-(dialkylamino)-1H-imidazoles

In the reaction of N,N-dialkyl-dichloromethaniminium chlorides 11 with 2-aminoacetophenones 12 , a general and simple route to heretofore unknown 5-aryl-substituted 2-(dialkylamino)-1,3-oxazolium salts 13 and 5-aryl-substituted 2-(dialkylamino)oxazoles 14 was found. From the 2-(dialkylamino)-1,3-oxazoles 14 , the corresponding oxazolium salts 13 were obtained after alkylation with (MeO)₂SO₂. The new oxazolium salts 13 were converted to 1-substituted 4-aryl-2-(dialkylamino)-1H-imidazoles 9 by treatment with NH₄OAc. The possible use of these 1H-imidazoles as dye educts was explored. Analytical data, as well as AM1 calculations, reveal some remarkable differences between the structures of the neutral imidazoles 9 and their positively charged oxazolium precursors 13 .