Norchlorcyclizine → tert-Butyl Cetirizine

Participants

Reaction Conditions

Reaction Steps

A suspension of 1-((4-chlorophenyl)phenylmethyl)piperazine (260 g, 0.9 mol), tert-butyl 2-(2-chloroethoxy)acetate (195 g, 1.0 mol), sodium hydroxide (106 g, 1 mol) and tert-butyl-ammonium bromide (“TABB”, 3.22 g, 0.01 mol, NOTE-TABB is a catalyst for this reaction) is dissolved in 2-butanone (“MEK”, 300 mL) heated to 150° C. and the water of reaction azeotroped over a period of about 4 hours. Heating is stopped and to the reaction mixture is added MEK (500 mL) added. The mixture is cooled to ambient, filtered and the solvent removed from the resulting solution by distillation under reduced pressure. The residue is dissolved in methyl tert-butylether (800 mL), washed with water (2×200 mL), saturated sodium chloride (2×100 mL) and the solvent removed under reduced pressure. The residue is treated with hexanes (1.8 mL) to afford tert-butyl (RS) 2-[2-[4-[(4-chlorophenyl)phenylmethyl]-1-piperazinyl]ethoxy]acetate as a white crystalline powder (260 g, 96% yield).

Provenance & Evidence