Imidazo pyridinones

Rearrangement of alkoxycarbonyl imidazole acryl azides in diphenyl ether at high temperatures afforded imidazo[l,5-c]pyrimidinone or imidazo[4,5-c]pyridinone derivatives <02TL5879>. Efficient synthesis of imidazopyridodiazepines from peri annulation in imidazo[l,2-a]pyridine has been described <02TL9119>. A convenient synthesis of 3,6-disubstituted-2-aminoimidazo[l, 2-a]pyridines has been published <02TL9051>. Novel 2,3-dihydroimidazo[2,l-h][l,3]oxazoles were prepared from intramolecular nucleophilic i/wo-substitution of 2-alkylsulfonylimidazoles <02S2691>. 4,4 -Bi-l//-imidazol-2-ones were efficiently synthesized from 5-amino-ot-imino-1 //-imidazole-4-acetonitriles and isocyanates <02JOC5546>. 

Rarrangement of A -alkoxycarbonylimidazole acyl azides 676 led to the formation of two products (Scheme 164). Imidazo[l,5-z]pyrimidinone 677 was formed when R was either Me or Et, although it was not clear how the alkyl transfer from imidazole to the pyrimidone occurred. With higher R groups (Pr or Ph), the anticipated imidazo[4,5-r-]pyridinone 678 was formed <2002TL5879>. 

The first report of the synthesis of an imidazo[4,S-6]pyridin-S--one by closure of a pyridine ring is a base-catalysed cyclization of the amino-malonylidene diester. Complementary to this method is that in which a monoester mononitrile of malonic acid is heated in acetic acid to give a high yield of the fused pyridinone. Me... 

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