A simple synthesis of 4-aroyl-5-methyl-1H-imidazol-2(3H)-one derivatives (Enoxymone analogues) from aryl methyl ketones via enaminones

Abstract

Aryl methyl ketones 1a-e gave with N,N-dimethylacetamide dimethylacetal (DMADMA) (E)-1- aryl-3-(dimethylamino)-but-2-en-1-ones 2a-e. Substitution of the N,N-(dimethylamino) group in the reaction with ammonium acetate afforded the corresponding (Z)-3-amino-1-aryl-but-2-en-1- ones 3a-e. In the reaction of 3a-e with diethyl azodicarboxylate intermediates 4a-e were formed, which were, in most cases without isolation, cyclized into ethyl (5-aroyl-4-methyl-2-oxo-2,3- dihydro-1H-imidazol-1-yl)carbamates 5a-e. Hydrolysis of the ester group, followed by the decarboxylation and deamination of intermediates 6a-c,e produced 4-aroyl-5-methyl-1Himidazol- 2(3H)-ones 7a-c,e.©ARKAT-USA, Inc.