p-Toluenesulfonic acid → HCID 11733337, compound

Participants

Reaction Conditions

Reaction Steps

A stirred solution of 10 g (41 mmol) of (S)-8-(acetoxy-methyl)-6,7,8,9-tetrahydropyrido[1,2-a]indole in 100ml of dichloromethane was treated dropwise at 0° C. with 4.3 ml (49 mmol) of oxalyl chloride. After 5 minutes, the solvent was removed by evaporation under reduced pressure. The residue was suspended in 150 ml of toluene and treated with 9.5 g (41 mmol) of isopropyl 1-methyl-3-indoleacetimidate hydrochloride (prepared as described in Example 1). The stirred suspension was cooled to 0° C. and treated dropwise with 23 ml (166 mmol) of triethylamine. After stirring for 18 hours at room temperature under nitrogen, the thick suspension was partitioned between dichloromethane, toluene and 0.5M hydrochloric acid. The organic extracts were dried over sodium sulfate, filtered and treated with a suspension of 15.6 g (82 mmol) of p-toluene sulfonic acid in 100 ml of toluene. The mixture was stirred at room temperature for 2.5 hours, washed with water, saturated sodium bicarbonate solution and brine, dried over sodium sulfate and evaporated to give a brown solid. Trituration with diethyl ether gave 13.73 g 72% of (S)-3-[8-(acetoxymethyl)-6,7,8,9tetrahydropyrido[1,2-a ]indol- 10-yl ]-4-(1-methyl-3-indolyl)-1H-pyrrole-2,5-dione. A sample was crystallized from dichloromethane/methanol to give an orange solid of melting point 238°-241° C.

Provenance & Evidence