[C:1](Cl)(=O)C(Cl)=O.[N:7]1[C:16]2[C:11](=[CH:12][CH:13]=[CH:14][CH:15]=2)[C:10]([C:17]([O-:19])=[O:18])=[CH:9][N:8]=1.[K+].N1C=CC=CC=1.CO>C1(C)C=CC=CC=1>[N:7]1[C:16]2[C:11](=[CH:12][CH:13]=[CH:14][CH:15]=2)[C:10]([C:17]([O:19][CH3:1])=[O:18])=[CH:9][N:8]=1A solution of 0.64 g of oxalyl chloride in 5 ml of dry toluene was added over 5 minutes to a stirred suspension of 0.98 g of 2 in 10 ml of dry toluene, at 0° C. The resulting mixture was stirred for 20 minutes at 0° C., for 30 minutes at room temperature, and for one hour at 80° C. The mixture was cooled and added in portions over 5 minutes to a stirred ice cold mixture of 0.4 g of pyridine, 0.32 g of methanol and 10 ml of dry toluene. The resulting mixture was held overnight at room temperature, then stripped in a rotary evaporator, and the residue was chromatographed over silica gel, using 5% ethyl acetate/methylene chloride mixture as eluent, to give 4, as yellow crystals, m.p.: 57°-58° C.
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