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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.

2‐Pyridin‐3‐ylbenzoxazoles were synthesized by the reaction between 3‐pyridinecarboxaldehyde and substituted o‐aminophenols in the presence of iodobenzene diacetate. The resulting benzoxazoles 3 were treated with methyl iodide to give the corresponding pyridinium salts 4 which underwent the hydride reduction with sodium borohydride or sodium cyanoborohydride to produce 2‐(1‐methyl‐1,2,5,6‐tetrahy‐dropyridin‐3‐yl)benzoxazole borane complex derivatives.

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 [ 3 H]‐NMS binding assay

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