Sodium Hydroxide → 2-[(1-Ethyl-2-methyl3-indolyl)carbonyl]-5-aminobenzoic acid

Participants

Reaction Conditions

Reaction Steps

To a solution of 7.04 g (0.02 mole) of 2-[(1-ethyl-2-methyl-3-indoly)carbonyl]-5-nitrobenzoic acid, prepared as described in part A of this example, in 70 ml of concentrated hydrochloric acid, there was added 13.5 g (0.06 mole) of stannous chloride dihydrate at such a rate as to allow the reaction to exotherm to 55° C. The temperature was maintained at 55° C. for an additional one-half hour. The reaction was then cooled to room temperature and the pH adjusted to six by the addition of 10 percent aqueous sodium hydroxide solution. The red precipitate thus formed was filtered off and extracted into acetone. The acetone solution was evaporated and the paste-like residue was slurried in diethylether and then the solid was collected by filtration to obtain 3.5 of 2-[(1-ethyl-2-methyl-3-indolyl)-carbonyl]-5-aminobenzoic acid (Formula VIII: R3 =R2 =R°=Y1 =H; R1 =NH2 ; R5 =CH3 ; R 6 =CH2CH3), a red solid which melted at 187°-189° C. E. A mixture of 3.22 g (0.01 mole) of 2-[(1-ethyl-2-methyl-3-indolyl)carbonyl]-5-aminobenzoic acid, 118 g (0.01 mole) of N,N,N',N'-tetramethyl-m-phenylenediamine in 10.0 ml of acetic anhydride was heated to 50° C. for one-half hour. After cooling to ambient temperature, 50 ml of water was added and the reaction mixture was filtered. The filtrate was rendered alkaline with dilute aqueous sodium hydroxide in the presence of 100 ml of toluene. The toluene layer was separated, dried and evaporated to obtain as tan crystals 3-[2,4-bis(dimethylamino)phenyl]-3-(1-ethyl-2-methyl-3-indolyl)-6-acetamidophthalide (Formula III: R°=R1 =R3 =Y1 =H; R2 =NHCOCH3 ; R=R5 =CH3 ; R4 =N(CH3)2 ; R6 =CH2CH3) having a melting point of 204°-206° C. Infrared analyses showed maxima at 1733 cm-1 (C=O; s) and 1695 cm-1 (C=O; s). Nuclear magnetic resonance analysis was consistent with the structure. An acetone solution of the above compound developed an intense grape color when spotted on silica gel.

Provenance & Evidence