Acetone → (1S,3S)-1-(1,3-Benzodioxol-5-yl)-2-(2-chloroacetyl)-2,3,4,9-tetrahydro-1H-pyrido[3,4-b]indole-3-carboxylic Acid Methyl Ester

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Reaction Steps

Cis 1-benzo[1,3]dioxol-5-yl-2,3,4,9-tetrahydro-1H-beta-carboline-3-carboxylic acid methyl ester hydrochloride of Step 2 (50 g) was dissolved in dichloromethane and 5% aqueous sodium bicarbonate (500 mL). The organic layer was separated and washed with deionized water (500 mL). The organic layer was added into deionized water (50 mL) and treated with sodium bicarbonate (15 g) at 25° C. to 30° C. To the resultant mixture, chloroacetyl chloride (25 g) in dichloromethane (50 mL) was added at a rate sufficient to maintain the temperature of the reaction mixture between 0° C. and 5° C. The reaction mixture was stirred for three hours. After the completion of reaction, dichloromethane (500 mL) and DI water (1 L) were added. The organic layer was separated and washed sequentially with water followed by aqueous sodium bicarbonate solution until the pH was 6.5-7.0, and finally with water. The organic layer was concentrated under reduced pressure to obtain a solid. The solid was dissolved in acetone (750 mL) and the resultant solution was concentrated to a residual volume of about 75 mL. To the concentrated solution, deionized water was slowly added at 20° C. to 25° C. and the resultant mixture was cooled to 0° C. to 5° C. with continuous stirring for 0.5 hours. The solid so obtained was filtered and dried to afford cis 1-benzo[1,3]dioxol-5-yl-2-(2-chloro-acetyl)-2,3,4,9-tetrahydro-1H-beta-carboline-3-carboxylic acid methyl ester.

Provenance & Evidence