Pentapeptides, processes for their preparation, intermediates used in such processes, use in pharmaceutical compositions and compositions containing them.

摘要

Pentapeptides of formula
wherein R¹ is hydrogen, methyl, ethyl, propyl, 2-methyl-2--pentenyl, 2-methyl-1-pentenyl, cyclopropylmethyl, or cyclobutylmethyl; R², R³ and R⁴ are, independently, hydrogen or methyl; X² represents COX wherein X is -OH, -NH₂, -NHCn-H₂n, +₁, where n is 1, 2, 3 or 4, -OR^s wherein R⁵ is lower alkyl of 1 to 4 carbon atoms, or X² represents CH₂OR⁶ wherein R⁶ is hydrogen or lower alkyl of 1 to 4 carbon atoms or a pharmaceutically acceptable salt thereof: have analgesic activity upon administration to warm-blooded animals. They are prepared by classical or solid phase synthetic methods via appropriate protected pentapeptides. Pharmaceutical compositions are also disclosed.