Imidazo pyrimidinones

A number of pyrimidines fused to five- or six-membered rings have been degraded to substituted pyrimidines and many of these reactions have been summarized elsewhere <1994HC(52)1>. A recent example used Raney nickel to remove a sulfur atom from the imidazo[4, 5 4,5]thieno[3,2-r/]pyrimidinone 966 <20010L3209, 2002JOC3365>. 

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>. 

Guo T, Hunter RC et al (2007) Microwave assisted synthesis of isothiazolo-, thiazolo-, imidazo-, and pyrimido-pyrimidinones as novel MCHIR antagonists. Tetrahedron Lett 48 613-615... 

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 pyrimidinones (170), formed from /3-aminocrotonamide and A -acyl-glycinates, cyclize on treatment with polyphosphoric acid, initially to imidazo[l,5-fl]pyrimidines (171) at higher temperatures, imidazopyridines (172) are formed (Scheme 83). ... 

---