Acetic Anhydride → 3-Cyano-6,6-dimethyl-11-oxo-6,11-dihydro-5H-benzo[b]carbazol-8-carboxylic acid

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Reaction Conditions

Reaction Steps

Under nitrogen atmosphere, to the dimethyl formamide (3 ml) solution comprising trifluoro-methanesulfonic acid 3-cyano-6,6-dimethyl-11-oxo-6,11-dihydro-5H-benzo[b]carbazol-8-yl ester (Compound B1, 150 mg, 0.345 mmol), lithium formate monohydrate (90 mg, 5.0 eq.), 4,5-bis(diphenylphosphino)-9,9-dimethylxanthene (Xantphos) (20 mg, 0.1 eq.), Pd2(dba)3 (32 mg, 0.1 eq.), lithium chloride (88 mg, 6.0 eq.), N,N-diisopropylethylamine (241 μl, 4.0 eq.), and acetic anhydride (131 μl, 4.0 eq.) were added, and the mixture was stirred at 80° C. for 15 hr. Upon the completion of the reaction, ethyl acetate was added to the reaction solution. The organic layer was washed in order with 1 M hydrochloric acid, distilled water, and brine. The organic layer was dried over sodium sulfate. The drying agent was removed by filtration and the residues obtained after concentration under reduced pressure were purified by silica gel column chromatography (ethyl acetate/hexane) to obtain the title compound (88 mg, 76%).

Provenance & Evidence