Formaldehyde → 8-(4-Methylpiperazin-1-yl)-5-(thiophen-2-yl)tetrazolo[1,5-a]pyrazine

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Reaction Steps

A 2 L round bottom flask was charged with 8-(piperazin-1-yl)-5-(thiophen-2-yl)tetrazolo[1,5-a]pyrazine HCl salt (139 g, 0.429 mol), HCHO (38% aqueous solution, 50 mL), NaBH3(CN) (90.7 g, 1.44 mol), CH2Cl2 (500 mL), and MeOH (200 mL). The resulting solution was stirred at room temperature for 0.5 h. Work-up: the reaction mixture was poured into saturated aqueous NaHCO3 and extracted with CH2Cl2 (500 mL×3). The combined organic layers were dried over anhydrous Na2SO4 and concentrated in vacuo. The residue was further purified by flash column chromatography on silica gel with 1-10% MeOH in CH2Cl2, to afford 122 g (94%) of the product as a yellow solid. 1H NMR (300 MHz, CDCl3) δ: 8.00 (m, 2H), 7.45 (dd, J=5.1, 1.2 Hz, 1H), 7.20 (dd, J=5.1, 3.6 Hz, 1H), 4.39 (br, 4H), 2.60 (t, J=5.1 Hz, 4H), 2.37 (s, 3H). MS m/z: 302 (M+H+).

Provenance & Evidence