Reaction of 1, 2, 3, 4-Tetrahydroquinazolin-4-ones with Acid Anhydride. II

Abstract

The reaction of 1, 2, 3, 4-tetrahydroquinazoline-2-spirocyclohexan-4-one (1b) with acetic anhydride and pyridine gave 1-(1-cyclohexenyl)-2-methyl-1, 4-dihydroquinazolin-4-one (3b). Compound 3b gave 3-acetyl-1-(1-cyclohexenyl)-2-methyl-1, 2, 3, 4-tetrahydroquinazolin-4-one (8b) upon reduction with NaBH₄ followed by acetylation with acetic anhydride. The position of the acetyl group of 8b was determined by comparison of its NMR spectrum with those of related compounds (9, 10, 11, 12, and 13).