Synthesis of New [1,3]Selenazolo[5,4-d]Pyrimidine Derivatives as Purine-Like Selenium-Containing Heterocycles

In the research, we presented a method for synthesizing selenium-containing heterocyclic compounds. One of the key structures in this project is the derivative of 7-methyl-2-(alkylthio)-5-(amino-1-yl)-[1,3]selenazolo[5,4-d]pyrimidine (3a-i). These are synthesized in one step using the treatment of precursor 2,4-dichloro-6-methylpyrimidin-5-amine (1) with selenium and sodium borohydride in ethanol to obtain the compound, which subsequently reacts with carbon disulfide in pyridine to form 5-chloro-7-methyl-[1,3]selenazolo[5,4-d]pyrimidine-2(1H)-thione (2). This is then treated with various alkyl halides under reflux conditions in ethanol to yield various derivatives (3a-i). A mixture of 5-chloro-7-methyl-2-(alkylthio)-[1,3]selenazolo[5,4-d]pyrimidine (3a-i) and various primary and secondary amines is refluxed in ethanol to prepare the corresponding nucleophilic substituted products, 2-(alkylsulfanyl)-7-methyl-5-(morpholin-4-yl)-[1,3]selenazolo[5,4-d]pyrimidines (4a-i) in good yields.