Synthesis and antibacterial activities of novel pyrimidines derived from 2-oxo (or thioxo)-4-phenyl-5-carbethoxy-6-methyl-1,2,3,4-tetrahydropyrimidine

The 2-oxo (or thioxo)-4-phenyl-5-carbethoxy-6-methyl-1,2,3,4-tetrahydropyrimidine (1a-c) were prepared. Heating a mixture of (1a-c, X=S) in 1,2-dibromoethane or chloroacetylchloride gave the thiazolopyrimidines (2a-c) and (3a-c) respectively. Acetylation of (1a-c, X=S) with acetic anhydride and acetic acid yielded the products (3a-c). Alkylation of (1a-c, X=S) with alkyl halide in alkaline medium in 1 : 2 and 1 : 1 ratios gave only monoalkyl derivatives (4a-c). Additional proof for the site of substitution was obtained by alternative synthesis of product (6a-c) through methylation of (5a-c). Product (1a, X=O) on acylation and alkylation in (1a-c, X=S) conditions gave structures 7 and 8 respectively, and reaction with POCl3 afforded 3-formyl-2-oxopyrimidine (9) in good yield. Some of these products were screened for antibacterial activity.