Cyclopropylamine → 1,8-Diazabicyclo(5.4.0)undec-7-ene

Participants

Reaction Steps

A solution of 20.6 g of ethyl 2-(2,7-dichloro-6-fluoroquinoline-3-carbonyl)-3-dimethylaminoacrylate and 6 g of cyclopropylamine in 100 cm3 of trichloromethane is stirred at a temperature close to 20° C. for 24 hours. The reaction mixture is concentrated under reduced pressure (20 kPa) at 50° C. The residue is taken up in 180 cm3 of ethanol and 10 g of DBU and the solution obtained is heated at a temperature close to 78° C. for 4 hours. After cooling to a temperature close to 20° C., the precipitate obtained is drained and washed with twice 60 cm3 of ethanol. 13.65 g of 8-chloro-1-cyclopropyl-3-ethoxycarbonyl-7-fluoro-4-oxo-1,4-dihydro-benzo[b][1,8]naphthyridine are obtained in the form of a pale yellow solid melting at 256° C., which is used for the subsequent steps without further purification.

Provenance & Evidence