Ciba-geigy Corporation

Peter Burckhardt

Pier G Ferrini

N-Benzoyl-N'-(2-phenylethyl)-piperazines of formula I ##STR1## wherein R.sub.1, R.sub.2, R.sub.3, R.sub.4 and R.sub.5 have the meanings as defined in the specification, and salts thereof, have analgesic properties and can be used as analgesic active ingredients in medicaments. They are prepared, for example, as follows: a compound of formula II ##STR2## wherein X.sub.1 is carboxy or reactive functionally modified carboxy, or a salt thereof, is reacted with a compound of formula III ##STR3## wherein X.sub.2 is hydrogen.

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Basel, Switzerland

Peter Burckhardt