2-(1,3-Dioxolanyl)-3-aminopyridine → 2-((3-Aminopyridin-2-yl)methylene)hydrazinecarbothioamide

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Reaction Steps

To a solution of 2-(1,3-dioxolanyl)-3-aminopyridine (0.80 g, 4.8 mmol) in 10 mL of ethanol, 8 mL of water and 2 mL of concentrated hydrochloric acid was added 0.48 g (5.3 mmol) of thiosemicarbazide. The mixture was stirred at room temperature overnight and refluxed for 1 h, cooled and filtered. The crude yellow hydrochloride salt was dissolved in 50 mL of hot water and filtered. To the hot filtrate was added 10 mL of 5% sodium bicarbonate solution. The mixture was stirred at room temperature for 1 h, filtered and washed with water, followed by ethanol to yield 3-amino-2-formylpyridine thiosemicarbazone. Yield: 0.72 g (77%); mp 240°-241° C. dec; MS m/e 194 (M+); 1H NMR (90 MHz, DMSO-d6) δ 6.48 (br s, 2H, 3-NH2, D2O exchangeable), 7.12 (m, 2H, 4-H and 6-H), 7.83 (dd, 1H, 5-H), 8.10 (br s, 2H, CSNH2, D2O exchangeable), 8.10 (s, 1H, 2-CH), 10.95 (s, 1H, NNH, D2O exchangeable). Anal. (C7H9N5S) C, H, N.

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