Coupling of 2-chloro-5-nitropyridine (II) with the sodium alkoxide of 5-methyl-2-phenylisoxazol-4-ylmethanol (I) gave the 2-alkoxy-5-nitropyridine (III), which was reduced to the aminopyridine (IV) by catalytic hydrogenation over Pd/C. Meerwein arylation of methyl acrylate with the diazonium salt generated from amine (IV) furnished the bromopropionate (V), which was further dehydrohalogenated in the presence of DBU to the pyridyl acrylate (VI). Ester reduction in (VI) employing DIBAL yielded the allylic alcohol (VII). This was hydrogenated to the saturated alcohol (VIII) in the presence of Pd/C. After activation of alcohol (VIII) as the corresponding mesylate (IX), displacement by KCN in hot DMF yielded nitrile (X). This was finally converted to the desired tetrazole by treatment with sodium azide and ammonium chloride.

Coupling of 2-chloro-5-nitropyridine (II) with the sodium alkoxide of 5-methyl-2-phenylisoxazol-4-ylmethanol (I) gave the 2-alkoxy-5-nitropyridine (III), which was reduced to the aminopyridine (IV) by catalytic hydrogenation over Pd/C. Meerwein arylation of methyl acrylate with the diazonium salt generated from amine (IV) furnished the bromopropionate (V), which was further dehydrohalogenated in the presence of DBU to the pyridyl acrylate (VI). Ester reduction in (VI) employing DIBAL yielded the allylic alcohol (VII). This was hydrogenated to the saturated alcohol (VIII) in the presence of Pd/C. After activation of alcohol (VIII) as the corresponding mesylate (IX), displacement by KCN in hot DMF yielded nitrile (X). This was finally converted to the desired tetrazole by treatment with sodium azide and ammonium chloride.