Synthesis of Some New Pyrimidine Derivatives of Expected Antimicrobial Activity

Abstract

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 α, β -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 3b with diethylmaleate and/or maleic anhydride. Formation of 1,3,4-oxadiazole 17 , pyrazoles 18 and 19 where obtained by treating the hydrazide 11 with carbon disulphide, triethyl orthoformate and acetylacetone respectively. While, reaction of 11 with p-chlorobenzaldehyde 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, ¹ H, and ¹³ C NMR spectra and microanalysis. Selected members of the synthesized compound were screened for antimicrobial activity.