3-Hydroxypicolinamide → 3-Hydroxythiopicolinamide

Beteiligte Stoffe

Reaktionsschritte

A stirred solution of 3-hydroxypicolinamide (1.35 g, 9.75 mmol) and Lawesson's reagent (2.37 g, 5.85 mmol) in dry ClCH2CH2Cl (12 mL) was heated to reflux under nitrogen for 5 hr. At ambient temperature, he mixture was diluted with EtOAc (50 mL), washed with half-saturated aq. NaCl (30 mL) containing NaHCO3 (840 mg) and with brine (20 mL). After drying over MgSO4 and filtration, the filtrate was concentrated in vacuo to give a brown solid, which was subject to flash chromatography on silica gel (CH2Cl2 as eluent) to provide 3c (623 mg, 42%) as a greenish yellow solid after crystallization from EtOAc/hexane. mp 152.0°-153.0° C.; IR (KBr) 3372, 3259, 2464, 1626, 1458, 1317 cm-1 ; 1HNMR (DMSO-d6) δ7.33 (1H, dd, J=8.6 and 1.0 Hz, Ar), 7.46 (1H, dd, J=8.6 and 4.3 Hz, Ar), 8.07-8.10 (1H, m, Ar), 8.15(1H, s, NH), 8.49 (1H, s, NH), 12.76 (1H, s, OH); FABMS m/z 154 (M+); Anal. Calcd for C6H6N2OS: C, 46.74; H, 3.92; N, 18.17. Found: C, 46.83H, 3.89; N, 17.90.

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