Reactions of lead tetra-acetate. Part III. Formation of pyrimidine-iones and related compounds from dicarboxylic acid amides

Abstract

Treatment of phthalamide (X) with lead tetra-acetate in dimethylformamide affords 1,2,3,4-tetrahydro-2,4-dioxoquinazoline (XI). Pyridine-2,3- and -3,4-dicarboxamide, succinamide, 2-phenylsuccinamide, and suitable N-monoalkyl diamides undergo similar cyclization reactions. Phthalamic acid (I) and 2-carbamylnicotinic acid (VI) yield appropriate oxizine derivatives (III) and (VII), when heated with lead tetra-acetate, but the method fails with 2-phenylsuccinamic acid (VIII). The mechanism of these transformations appears to involve initial formation of isocyanates.