9-Bromo-4-oxo-4,5-dihydro-6-oxa-3-thia-1-aza-benzo[e]azulene-2-carboxylic acid methyl ester → 9-Bromo-4-hydroxy-4-methyl-4,5-dihydro-6-oxa-3-thia-1-aza-benzo[e]azulene-2-carboxylic acid methyl ester

Beteiligte Stoffe

Reaktionsbedingungen

Reaktionsschritte

To a stirred solution of 9-Bromo-4-oxo-4,5-dihydro-6-oxa-3-thia-1-aza-benzo[e]azulene-2-carboxylic acid methyl ester (500 mg, 1.41 mmol) in THF (20 mL) at −70° C., was added MeMgBr (1.8 M in THF, 1.57 mL, 2.82 mmol) dropwise. The reaction was stirred at −70° C. for 3 h, and then warmed to −30° C. for 1 h. The reaction mixture was quenched with saturated aqueous NH4Cl solution at −30° C. and extracted with EtOAc (20 mL×2). The combined organic layers were washed with brine, dried over Na2SO4, concentrated and purified by flash column chromatography (silica gel, EtOAc in hexane from 0 to 30%) to give 9-Bromo-4-hydroxy-4-methyl-4,5-dihydro-6-oxa-3-thia-1-aza-benzo[e]azulene-2-carboxylic acid methyl ester as a yellow solid (387 mg, 74%) LC-MS (ESI & APCI): 372.2 (M+2).

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