Triethylamine → ethyl 4-(2,3-dimethoxy-6,7-dihydro-5H-benzocyclohepten-8-ylcarbonyl)piperazine-2-carboxylate

Participants

Reaction Steps

A solution of 2,3-dimethoxy-6,7-dihydro-5H-benzocycloheptene-8-carbonylchloride (1.1 g) in dichloromethane (12 ml) is added dropwise, taking 30 minutes while stirring under ice-cooling, to a mixture of ethyl piperazine-2-carboxylate hydrochloride (1.0 g), triethylamine (0.5 g) and dichloromethane (20 ml). The reaction mixture is stirred for one hour at 0 ° C, and then poured into ice-water, followed by extraction with dichloromethane. The organic layer is washed with water and dried, then the solvent is distilled off under reduced pressure. The residue is purified by means of a silica gel column chromatography (hexane:ethyl acetate:acetone=1:1:1) to afford ethyl 4-(2,3-dimethoxy-6,7-dihydro-5H-benzocyclohepten-8-ylcarbonyl)piperazine-2-carboxylate as crystals (1.2 g). This product is recrystallized form ethyl acetate and hexane to give colorless prisms, m.p. 105-106° C.

Provenance & Evidence