Dichloromethane → HCID 70358081, compound

Participants

Reaction Steps

2 g (5.7 mmol) of 4-hydroxy-1-[(5-methoxybenzocyclobuten-1-yl)methyl]-1,2,5,6-tetrahydro-pyridine-3-carboxylic acid ethyl ester hydrochloride are introduced, at -80° C. under argon, into 80 ml of dichloromethane. While stirring, 1.08 ml (11.3 mmol) of boron tribromide are metered in. After 30 minutes at -80° C., the reaction mixture is gradually heated to +5° C. over a period of 2 hours while stirring. 40 ml of ethanol are then cautiously added and the whole is subsequently concentrated under a water-jet vacuum. The residue is dissolved in 150 ml of ethanol and again concentrated by evaporation under a water-jet vacuum. This procedure is repeated twice more. The resulting residue is then crystallised from ethanol/diethyl ether. 4-hydroxy-1-[(5-hydroxybenzocyclobuten-1-yl)methyl]-1,2,5,6-tetrahydro-pyridine-3-carboxylic acid ethyl ester hydrobromide and 1-[(5-hydroxybenzocyclobuten-1-yl)methyl]-4-oxo-piperidine-3-carboxylic acid ethyl ester hydrobromide of m.p. 192°-194° C. are obtained.

Provenance & Evidence