Synthesis of some new pyrimidine derivatives of expected antimicrobial activity

2-(2-Arylvinyl)-6-methyl-4-mercapto-5-acetylpyrimidine derivatives 3(a-d), were synthesized form the reaction of the appropriate isothiocyanate derivatives 1 with alpha,beta-unsaturated aminoketone 2. Compound 3 was alkylated with methyl iodide, ethyl chloroacetate and/or bromosugar to afford 6, 9, and 22(a-c) respectively. Cyanoethylation of 3(b) afforded 6(b) which upon cyclization with hydrazine hydrate gave pyrazolopyrimidine 7. Bromination of 6(b) gave dibromo compound 8. Thieno{[}2,3-d]pyrimidines 10 and 12 were obtained by ring closure of the alkylated product 9 with TEA/EtOH and/or through cyclization of the hydrazide 11 with NaOEt/EtOH. While, Thieno{[}2,3-d]pyrimidine 14 was obtained directly by alkylation of 3(b) with chloroacetone in both TEA/EtOH and Na2CO3 solution. The cycloaddition products 15 and 16 were obtained by reaction of 36 with diethylmaleate and l or maleic anhydride. Formation of 1,3,4-oxadiazole 17, pyrazoles18 and 19 where obtained by treating the hydrazide 11 with carbon disulphide, triethyl orthoformate and acetylacetone respectively. While, reaction of 11 with p-ehlorobenzaldehyde resulted in the Schiff's base 20 which, cyclizes with thioglycolic acid to afford thiazolidone 21. Hydrolysis of 22(a-c) in TEA/MeOH afforded the free sugar 23(a-c). The structures of all the new compounds were confirmed using IR, H-1, and C-13 NMR spectra and microanalysis. Selected members of the synthesized compound were screened for antimicrobial activity.