A new entry to the imidazo[4,5-d]pyrimidine system. The reaction of 1,3-dimethyl-6-aminouracil with N,N-dimethyldichloromethyleniminium chloride (phosgeniminium chloride) and trimethylsilyl azide

Article abstract of DOI:10.1002/jhet.5570310515

1,3-Dimethyl-6-aminouracil 2 was converted into various 8-N-arylaminotheophyllines (2-N-arylamino-4,6-dimethylimidazo[4,5-d]pyrimidine-(4H,6H)-5,7-diones ) 17 through reaction successively, with phosgeniminium chloride (N,N-dimethyldichloromethyleniminium chloride) (1a), trimethylsilyl azide (4) and arylamines. Starting with the synthesis of the N,N-dimethyl-(1,3-dimethyl-4-aminouracil-5 yl)chloromethyleniminiun chloride (amide chloride) 3 this new route to the imidazo[4,5-d]pyrimidine skeleton was shown to proceed via the formation of a very unstable N,N-dimethyl-(1,3-dimethyl-4-aminouracil-5-yl)azidomethyleniminium chloride (amide azide) (8) which would undergo an in situ rearrangement into very likely, a 4-amino-5-(chloroformamidin-1'-yl)uracil and/or related compounds of types 10. Depending on reaction conditions, the latter was proved to be a very good precursor of the 8-dimethylaminotheophylline 11 as well.