Dimethyl Sulfoxide → Methyl 13-cyclohexyl-6-formyl-5-methyl-6,7-dihydro-5H-indolo[1,2-d][1,4]benzodiazepine-10-carboxylate

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Reaction Conditions

Reaction Steps

DMSO (5 eq.) was dissolved in DCM and the solution was cooled to −78° C. At this temperature a 2 M solution of oxalylchloride in DCM (2.5 eq.) was added slowly and the mixture was stirred for 25 min at −78° C. A solution of dimethyl 13-cyclohexyl-5-methyl-6,7-dihydro-5H-indolo[1,2-d][1,4]benzodiazepine-6,10-dicarboxylate (1 eq.) in DCM (0.09 M) was added slowly at −78° C. and stirring was continued for 25 min at this temperature. Then NEt3 (8 eq.) was added and the resulting slurry was placed into an ice bath at 0° C. The mixture was left stirring for 90 min, then diluted with DCM and extracted with sat. aq. NH4Cl, sat. aq. NaHCO3 and brine. After drying over Na2SO4 all volatiles were evaporated in vacuo. The product was obtained as a deep-yellow solid, which was filtered with DCM over a pad of silica. After evaporation of the solvent the product was obtained as a yellowish solid (quant.). (ES+) m/z 417 (M+H)+.

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