Dimethylformamide → Ethyl 2-[(3-bromophenyl)methyl]-5-hydroxy-6-(1-methylethyl)-3-oxo-2,3-dihydro-4-pyridazinecarboxylate

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Reaction Steps

Ethyl 2-[(3-bromophenyl)methyl]-5-hydroxy-6-(1-methylethyl)-3-oxo-2,3-dihydro-4-pyridazinecarboxylate. To a solution of ethyl 5-hydroxy-6-(1-methylethyl)-3-oxo-2,3-dihydro-4-pyridazinecarboxylate (example 46(a), 3 g, 13.26 mmol) in N,N-Dimethylformamide (DMF) (50 ml) at 0° C. was added sodium hydride (0.796 g, 19.89 mmol) in portions. The reaction mixture was stirred at room temperature for 45 minutes and then cooled back to 0° C. and 3-bromobenzyl bromide (3.31 g, 13.26 mmol) was added portionwise. The mixture was stirred at ambient temperature for 2.5 hours then quenched with 1N HCl (10 ml) and diluted with water (30 ml). The aqueous solution was extracted with ethyl acetate (2×100 ml), the organic layers combined and washed with water (100 ml) and brine (100 ml), dried over Magnesium sulfate, filtered and solvents removed with rotary evaporation. The crude oil was purified by flash column chromatography (10-100% ethyl acetate in hexanes) to provide the title compound (ethyl 2-[(3-bromophenyl)methyl]-5-hydroxy-6-(1-methylethyl)-3-oxo-2,3-dihydro-4-pyridazinecarboxylate (890 mg, 1.801 mmol, 13.58% yield) as a pale yellow solid. The product isolated was a 5:1 mixture of the desired mono alkylated to the bis-alkylated(4-O-benzyl) (LCMS=564). 1H NMR (400 MHz, DMSO-d6) d ppm 12.33 (s, 1H), 7.46-7.53 (m, 2H), 7.24-7.35 (m, 2H), 5.14 (s, 2 H), 4.26 (q, J=7.07 Hz, 2H), 3.17 (sept, J=6.78 Hz, 1H), 1.26 (t, J=7.20 Hz, 3H), 1.16 (d, J=6.82 Hz, 6H). MS (ES+) m/e 396 [M+H]+.

Provenance & Evidence