Abstract
A new synthesis of 1, 3-dimethyl-6-azalumazines (isofervenulins) is described. The reaction of 6-amino-1, 3-dimethyl-5-nitrosouracil (I) with acid hydrazides in refluxing aprotic solvents such as dimethylformamide (DMF), dimethyl sulfoxide (DMSO) or sulfolane affords the corresponding 1, 3-dimethyl-6-azalumazines (II) along with byproducts, 2, 4, 9, 11-tetramethyl-8-azapurino [7, 8-f]-6-azapteridine-1, 3, 10, 12 (2H, 4H, 9H, -11H)-tetrones (III). These 8-azapurino [7, 8-f]-6-azapteridines were alternatively prepared by the condensation of II with 6-amino-1, 3-dimethyluracil in refluxing DMF. Compounds II were converted into 8-substituted theophyllines (V) by reductive ring contraction with sodium dithionite in formic acid.
