Application of Halogeno-Ketones to the Synthesis of Pteridines, Including Pteroic Acid

PTEROIC and pteroylglutamic acids were first synthesized from 2: 4: 5-triamino-6-hydroxypyrim-idine (I), 1: 2-dibromopropionaldehyde and p-amino-benzoic or p-aminobenzoylglutamic acids¹. The action of an α-halogenocarbonyl compound on a 4: 5-diaminopyrimidine introduces a new variation of the general method of pteridine synthesis remarkable for the spontaneous oxidation of the dihydro-pteridine initially obtained during the course of the reaction. It has been observed, however, that the formation of an intermediate dihydro derivative can sometimes be troublesome in that the hydrogen eliminated may effect the reduction of substituents². The use of 1: 1-dihalogeno-aldehyde or -ketone would, if successful, avoid this difficulty; but apart from Purrmann's somewhat analogous synthesis of xanthopterin from dichloracetic acid and the pyrimidine (I)³, it is a modification not hitherto investigated.