Cleavage of pyrimidines and fused pyrimidines by active methylene reagents with closure to give pyridine derivatives

Abstract

Pyrimidine and its 4-methyl derivative reacted with malononitrile to form 2-aminopyridine-3-carbonitrile and its 6-methyl derivative, respectively. Quinazoline with malononitrile gave 2-aminoquinoline-3-carbonitrile and, with dimedone, 3,4-dihydro-3,3-dimethyl-1 (2H)-acridone (16). Similarly pyrido[3,2-d]pyrimidine (9) and dimedone gave 6,7-dihydro-7,7-dimethylbenzo [b][1,5] naphthyridin-9(8H)-one (18). 4-Aminopyrimido[4,5-d] pyrimidine (10) and malononitrile yielded 4,7-diaminopyrido[2,3-d]pyrimidine-6-carbonitrile (19): purine and malononitrile gave 5-aminoimidazo[4,5-b]pyridine-6-carbonitrile (20). ¹H N.m.r. spectra are reported and the mechanisms of the reactions are discussed.