Synthesis of 2-sulfanyl-6-methyl-1,4-dihydropyrimidines as a new class of antifilarial agents.

A series of 2-sulfanyl-6-methyl-1,4-dihydropyrimidines (8-21) were synthesized in good yields by alkylation of 5-methyl-6-phenyl-2-thioxo-1,2,3,6-tetrahydropyrimidine-4-carboxylic acid ethyl esters (2-7) with different alkyl or aralkyl halides in the presence of a combination of anhydrous K(2)CO(3) and catalytic amount of tetrabutyl ammonium bromide. The title compounds were evaluated for their antifilarial activity against adult parasites of human lymphatic filarial parasite Brugia malayi (sub-periodic strain) in vitro and in vivo at various concentrations. One of the compounds (18) showed promising antifilarial activity.