Methyl 8-bromooctanoate → 1-(7-Methoxycarbonylheptyl)-3-methyl-2-(3-pyridyl)indole

Participants

Reaction Steps

Dimethylformamide (1640 ml) was charged into a 20 gallon glass kettle along with 430 g of potassium t-butoxide. This solution was stirred under nitrogen and cooled to -8°. A solution of 682 g of 3-methyl-2-(3-pyridyl)indole in 3280 ml of dimethylformamide was added over 0.75 hour while the temperature is maintained below 0°. After 2 hours of stirring of -10°, 1640 ml of a solution of 780 g of methyl 8-bromooctanoate in dimethylformamide was added over 1 hour. Reaction temperature was maintained below 0°. After 2 hours stirring, the reaction mixture was allowed to warm to room temperature overnight. The rust-colored mixture was then cooled to about 5° and treated with 19.7 L of ice water. The temperature rose to 25°. After 0.5 hour stirring, the mixture was extracted with 2×8 L of ether. The extracts were dried (MgSO4) and concentrated in vacuo to give the methyl ester of 1-(7-methoxycarbonylheptyl)-3-methyl-2-(3-pyridyl)indole as an oil. 1293 g of this oil was treated with 6.53 L of IN NaOH and warmed over steam to 90° for 2.5 hours. After cooling to room temperature, the solution was washed with 3×3 L of ether. The aqueous layer was cooled to 10° and acidified to pH 3.5 with 3.4 L of 2N HCl. The heavy suspension which resulted was extracted with 4×4 L of methylene chloride. The combined extracts were washed once with 4 L of water and dried (MgSO4). After filtration and evaporation of solvent in vacuo at 60°, ether (1.5 L) trituration of the residue and drying gave 1-(7-carboxyheptyl)-3-methyl-2-(3-pyridyl)indole, m.p. 113°-115°. Recrystallization from ethanol raised melting point to 114°-116°.

Provenance & Evidence