Iodine → 2-iodo-3-(2-methylsulfanyl-pyrimidin-4-yl)-6,7-dihydro-5H-pyrazolo[1,2-a]pyrazol-1-one

Participants

Reaction Conditions

Reaction Steps

To a cold (0° C.) solution of 3-(2-methylsulfanyl-pyrimidin-4-yl)-6,7-dihydro-5H-pyrazolo[1,2-a]pyrazol-1-one, 20, (4.7 g, 19.1 mmol), in carbon tetrachloride/pyridine (140 mL of 1:1 mixture) is added dropwise a solution of iodine in carbon tetrachloride/pyridine (80 mL of 1:1 mixture). After stirring at 0° C. for 30 min, the ice-bath is removed at the mixture was stirred at room temperature. After stirring at room temperature for 1 hour, the reaction mixture was poured into aqueous saturated Na2S2O3. The aqueous phase is extracted with EtOAc (×3). The combined organic phases are dried (MgSO4), filtered and concentrated in vacuo. The resulting yellow solid is purified by silica gel chromatography (5% MeOH/chloroform) to afford 4.2 g of the desired product. 1H NMR (300 MHz, CDCl3) δ 8.72 (d, J=5.1 Hz, 1H), 7.97 (d, J=5.1 Hz, 1H), 4.31 (t, J=6.9 Hz, 2H), 4.10 (t, J=6.9 Hz, 2H), 2.74 (dddd, J=6.9, 6.9, 6.9, 6.9 Hz, 2H), 2.62 (s, 3H); ESI+ MS: m/z (rel intensity) 375.0 (100, M++H).

Provenance & Evidence