Dimethylformamide → 6-Hydroxy-8-(5-phenyl-2-pentyloxy)-3a,4-dihydro(2H,3H)-pyrrolo[1,2-a]quinolin-1,5-dione

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Reaction Conditions

Reaction Steps

Under anhydrous conditions and in a nitrogen atmosphere, 70 g. (0.30 mole) 6,8-dihydroxy-3a,4-dihydro-(2H,3H)-pyrrolo[1,2-a]quinolin-1,5-dione was dissolved in 750 ml. dimethylformamide by warming to 60° C. To the resulting deep red solution was added 51.6 g. (0.675 mole) potassium carbonate. The mixture was heated to 70° C., a solution of 2-methylsulfonyloxy-5-phenylpentane in 250 ml. dimethylformamide was added in a fast stream, and heated at 75°-80° C. for 12 hours. Additional portions of 2-methylsulfonyloxy-5-phenylpentane (5.3 g.) and potassium carbonate (3.8 g.) and heating continued at 75°-80° C. for two hours. The mixture was poured over a mixture (one liter each) ethyl acetate and ice and, after shaking in a separtory funnel, the layers were separated. The aqueous phase was extracted with 5×1000 ml. ethyl acetate. The combined organic layers were washed with 3×4 liters water, 3×2 liters of 0.5N hydrochloric acid, dried (MgSO4) and concentrated to a volume of about 2.5 liters. Upon cooling, the precipitated product which formed was collected: 9.0 g., M.P. 151°-153° C. The mother liquor was concentrated to half volume, cooled, and a second crop, 34.2 g., M.P. 148°-151° C., was collected. Total yield by crystallization: 52.2 g. This material was shown to be primarily a single diastereomer, designated as "Diastereomer B." Upon recrystallization from ethyl acetate, colorless crystals were obtained, M.P. 159°-161° C. This was found to be about 90% diastereomer B. 1H--NMR (CDCl3) ppm (delta): 1.33 (d, 3H, J=6 Hz).

Provenance & Evidence