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.