Synthesis of 5‐(4‐Alkylsulfanyl‐[1, 2, 5]Thiadiazol‐3‐yl)‐3‐Methyl‐1, 2, 3, 4‐Tetrahydropyrimidine Oxalate Salts and their Evaluation as Muscarinic Receptor Agonists

The synthesis and biological test of 5‐(4‐alkylsulfanyl‐[1, 2, 5]thiadiazol‐3‐yl)‐3‐me‐thyl‐1, 2, 3, 4‐tetrahydropyrimidine oxalate salts 7 as muscarinic receptor agonists are described. The key intermediate 4 was obtained by a modified Strecker reaction and cyclization, and the 3‐methyl‐1, 2, 3, 4‐tetrahydropyrimidines were obtained by subsequent substitution, quarternization, and reduction. The final products 7 were obtained as oxalic acid salts. The prepared compounds were examined in vitro for their binding affinities to the cloned human muscarinic receptor by the [ 3 H]‐NMS binding assay.