| abstract |
Compounds of the formula <IMAGE> and pharmaceutically acceptable non-toxic acid addition salts thereof, in which R is hydrogen, methyl, or ethyl; A is the residue of a D-amino acid selected from the group consisting of Ala, Abu, Nva, Val, Nle, Leu, Ile, Gly(Al), Gly(Cp), Met, Cys(Me), Met(O), Cys(Me) (O), Ser, Thr, and Hse; R1 is hydrogen, C1-C3 primary alkyl, cyclopropylmethyl, allyl, or propargyl; X is bromo, iodo, chloro, C1-C3 alkyl, trifluoromethyl, or C1-C2 alkoxy; B is the residue of a D- or L-amino acid lacking its carboxyl moiety and selected from the group consisting of Gly, Ala, Abu, Nva, Val, Nle, Leu, Ile, Pgl, Cys(Me), Cys(Me) (O), Cys(Me) (O2), Cys(Et), Cys(Et) (O), Cys(Et) (O2), Met, Met(O), Met(O2), Eth, Eth(O), Eth(O2), Ser(Me), Ser(Et), Hse(Me), and Hse(Et) as well as any of such residues substituted at the amino nitrogen by a C1-C3 primary alkyl; Z is -CH2OR2, <IMAGE> in which R2 is hydrogen or C1-C3 alkyl; subject to the proviso that, when R1 is other than hydrogen, B is the residue of an amino acid that lacks substitution at the amino nitrogen; are useful analgesic agents. |