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

Synthesis of 2‐amino‐6‐hydroxymethyl‐4‐(3 H )pyrido[3,2‐ d ]pyrimidinone ( 5 ) from 2‐amino‐6‐methyl‐4‐(3 H )‐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‐(3 H )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.