Synthesis of 5-(4-alkoxy-[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 testing of 5-(4-alkoxy-[1,2,5]thiadiazol-3-yl)-3-methyl-1,2,3,4-tetrahydropyrimidine oxalate salts 8 as muscarinic receptor agonists are described. The key intermediate 4 was obtained by modified Strecker reaction and cyclization of starting material 1. Subsequent alkoxy substitution, quaternization and reduction afforded 7. For the sake of purity and stability of the final products 8, the 3-methyl-1,2,3,4-tetrahydropyrimidines were obtained as oxalic acid salts. All final compounds were examined in vitro for their binding affinities to the cloned human muscarinic receptor by the [H-3]-NMS binding assay.