Acetic Anhydride → 3-[2,4-Bis(dimethylamino)-phenyl]-3-(1-ethyl-2-methyl-3-indolyl)-4,5,6,7-tetrachlorophthalide

Participants

Reaction Steps

A stirred mixture of 8.86 g of 2-[(1-ethyl-2-methyl-3-indolyl)carbonyl]-3,4,5,6-tetrachlorobenzoic acid, prepared as described in part A above, 4.0 g of N,N,N',N'-tetramethyl-m-phenylenediamine, and 10.0 ml of acetic anhydride was heated at reflux for a period of three hours. The reaction was then allowed to cool to room temperature, and the tan precipitate which formed was filtered and washed with isopropanol. The material thus obtained was dissolved in 500 ml of benzene and the resulting solution extracted with 70 ml of 10 percent aqueous sodium hydroxide. The benzene solution was filtered and evaporated to dryness at ambient temperature yielding 1.5 g of 3-[2,4-bis(dimethylamino)phenyl]-3-(1-ethyl-2-methyl-3-indolyl)-4,5,6,7-tetrachlorophthalide (Formula III: R0 =R1 =R2 =R3 =Cl; R=R5 =CH3 ; R4 =N(CH3)2 ; R6 =CH2CH3 ; Y1 =H), a white solid which melted with decomposition at 227°-229° C. A significant infrared maximum occurred at 1770 cm-1 (C=O; s). The nuclear magnetic resonance spectrum was in complete agreement with the assigned structure. A benzene solution of this product spotted on silica gel developed an intense purple color.

Provenance & Evidence