5‐Cyano‐6‐aryluracil and 2‐thiouracil derivatives as potential chemotherapeutic agents. IV

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Abstract
A series of 5‐cyano‐6‐aryluracils and 2‐thiouracils1a‐hhas been prepared and alkylated to 1,3‐dialkyluracils2a‐dand 2‐alkylthiouracils,3, 4and6, by electrophilic substitution with alkyl halides. Reaction of1bwith dibromoethane and 1,3‐dibromopropane gave the corresponding bicyclic products, 7‐aryl‐6‐cyano‐2,3‐dihydrothiazolo[3,2‐a]pyrimidin‐5‐ones5a,band 8‐aryl‐7‐cyano‐3,4‐dihydro‐2H‐pyrimido[2,3‐b][1,3]thiazin‐6‐ones5c‐g. Nucleophilic substitution on6with hydrazine led to7which on refluxing with formic acid gave 5‐aryl‐6‐cyano‐8‐methyl‐s‐triazolo[3,4‐b]pyrimidin‐7‐ones (9), while with acetic and propionic acids only 2‐acylhydrazino‐3‐methyl‐4‐oxo‐5‐cyano‐6‐arylpyrimidines8a,bwere isolated. The hydrazine7undergoes cyclization with acetylacetone and methyl dimethylmercaptoacrylate providing 2‐(pyrazol‐1‐yl)‐3‐methyl‐4‐oxo‐5‐cyano‐6‐substituted pyrimidines10, and11. Some of the compounds were screened for antibacterial‐, antifungal‐ and antiviral activities and a few of them showed significant chemotherapeutical activities.