Boron tribromide → 4-Acetyl-1-ethyl-2-(4-hydroxyphenyl)-6-methoxypyrrolo[2,1,5-cd]indolizine

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Reaction Steps

A solution of 4-acetyl-1-ethyl-6-methoxy-2-(4-methoxyphenyl)pyrrolo[2,1,5-cd]indolizine (0.3 g, 0.85 mmol) in 7 ml of dry dichloromethane was cooled to -65° C. and stirred in a nitrogen atmosphere while 1.2 ml of a 1 M boron tribromide solution in dichloromethane was added. Stirring was continued for one hour and the cooling source was removed. The reaction mixture was allowed to reach room temperature and then poured into a stirred medium of dichloromethane (100 ml) and a saturated sodium hydrogen carbonate solution (100 ml). The usual work up afforded 200 mg of a substance which was submitted to column chromatography (aluminium oxide) with dichloromethane/methanol (20:1) as eluent. The fractions having RF 0.4 (silica gel 60, dichloromethane/methanol (20:1)) was collected and evaporated to afford 160 mg (58%) of the title compound. M.p. 245-46° C. 1H-NMR (DMSO-d6, 200 MHz) δ: 1.37 (t, 3H), 2.62 (s, 3H), 3.13 (q, 2H), 4.07 (s, 3H), 7.00 (d, 2H), 7.70 (d, 2H), 7.79 (d, 1H), 7.87 (d, 1H), 8.12 (s, 1H), 9.87 (s, 1H). (Compound 7).

Provenance & Evidence