1-Methylpiperazine → Zolenzepine

Participants

Reaction Steps

3.5 g of 4-chloroacetyl-1,3-dimethyl-1,4,9,10-tetrahydropyrazolo[4,3-b][1,5]benzodiazepin-10-one, 8.1 g of N-methylpiperazine and 50 ml of toluene are stirred at 80° C. for 2 hours. 60 ml of dilute sodium bicarbonate solution are added to the mixture, the layers are separated and the aqueous phase is extracted by shaking it with toluene several times more before concentrating it to dryness in vacuo. The residue is stirred with 100 ml of isopropanol and is filtered; the filtrate is concentrated in vacuo. The residue (4.0 g) is purified by stirring it with diethyl ether and by recrystallizing it from toluene, which yields 2.2 g of 1,3-dimethyl-4-[(4-methylpiperazin-1-yl)acetyl]-1,4,9,10-tetrahydropyrazolo[4,3-b][1,5]benzodiazepin-10-one, mp 186° to 188° C.; succinate, mp 172° to 174° C.

Provenance & Evidence