3-Bromopropionic acid → 1,1,2-trimethyl[1H]-benz[e]indole-3-propanoic acid

Beteiligte Stoffe

Reaktionsbedingungen

Reaktionsschritte

To synthesize cypate, a mixture of 1,1,2-trimethyl-[1H]-benz[e]indole (40.0 g, 19.11 mmol) and 3-bromopropanoic acid (40.0 g, 26.15 mmol) in 1,2-dichlorobenzene (200 mL) was heated at 110° C. for 18 h. After the resulting mixture was cooled to room temperature, the precipitate was collected by filtration, followed by trituration in dichloromethane (DCM) to remove the un-reacted material, and then dried under vacuum to afford 1,1,2-trimethyl[1H]-benz[e]indole-3-propanoic acid. A solution of acetic anhydride (1.20 g, 11.75 mmol) in DCM (5 mL) was added dropwise to a cooled suspension of glutaconaldehyde dianil monohydrochloride (2.84 g, 9.97 mmol) and diisopropylethylamine (DIEA, 2.60 g, 20.11 mmol) in DCM (20 mL). The resulting clear solution was stirred for 1 h and added dropwise to a refluxing solution of 1,1,2-trimethyl[1H]-benz[e]indole-3-propanoic acid (8.2 g, 22.64 mmol) and sodium acetate (3.2 g, 39.01 mmol) in acetonitrile/water (95/5 mL). The mixture was refluxed for 16 h, cooled, filtered, and washed with acetonitrile, 5% HCl solution and ethyl ether. About 6 g (85%) of cypate was obtained. It was further purified by recrystallization from 30% acetonitrile in water. Mass calculated: 625; observed (ESI-MS): 625.34 [M]+.

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