Synthesis and antimicrobial testing of 2‐amino‐6‐hydroxymethyl‐4‐(3H)pyrido[3,2‐d]pyrimidinone

Synthesis of 2‐amino‐6‐hydroxymethyl‐4‐(3H)pyrido[3,2‐d]pyrimidinone (5) from 2‐amino‐6‐methyl‐4‐(3H)‐pyrido[3,2‐d]pyrimidinone (2) was accomplished by selenium dioxide oxidation of 2 to the aldehyde 4 followed by sodium borohydride reduction. Compound 2 was available in four steps from 5‐aminouracil or in two steps from 5‐nitroisocytosine (3a). Catalytic reduction of 4 or 5 gave a mixture of 2‐amino‐6‐methyl‐5,6,7,8‐tetrahydro‐4‐(3H)pyrido[3,2‐d]pyrimidinone (6a) and the 6‐hydroxymethyl compound 6b. These compounds showed only weak inhibitory activity in the coupled reactions catalyzed by 7,8‐dihydro‐6‐hydroxymethylpterin pyrophosphokinase and 7,8‐dihydropteroate synthetase from E. Coli. No significant antibacterial activity was observed.