1-Cyclopropyl-3-ethoxycarbonyl-7,8,9-trifluoro-4-oxo-1,4-dihydrobenzo[b][1,8]naphthyridine → Ethyl 1-cyclopropyl-7,9-difluoro-8-(4-furfurylpiperazin-1-yl)-4-oxo-1,4-dihydrobenzo[b][1,8]naphthyridine-3-carboxylate

Participants

Reaction Steps

Ethyl 1-cyclopropyl-7,9-difluoro-8-(4-furfurylpiperazin-1-yl)-4-oxo-1,4-dihydrobenzo[b][1,8]naphthyridine-3-carboxylate was prepared under the conditions of Example 3, but from 1.8 g of ethyl 1-cyclopropyl-7,8,9-trifluoro-4-oxo-1,4-dihydrobenzo-[b][1,8]naphthyridine-3-carboxylate and 4.8 g of 4-furfurylpiperazine hydrochloride in 30 cm3 of dimethyl sulphoxide and 5.2 cm3 of triethylamine. 1.5 g of ethyl 1-cyclopropyl-7,9-difluoro-8-(4-furfurylpiperazin-1-yl)-4-oxo-1,4-dihydrobenzo[b][1,8]naphthyridine-3-carboxylate were obtained in the form of a yellow-brown solid melting at about 125-128° C., which solid was used without additional purification in the subsequent stages.

Provenance & Evidence