Compounds of the formula
and pharmaceutically acceptable non-toxic acid addition salts thereof, in which L and D definethe chirality;
R, is hydrogen or C1-C3 primary alkyl;
R2 is C1-C4 primary or secondary alkyl, allyl, cyclopropylmethyl, C1-C2 hydroxyalkyl, or -(CH2)m-U-CH3 in which U is -S- or
and m is 1 or2;
R3 is cyclopropylmethyl or allyl; and Z is
in which R4 is hydrogen, acetyl, or acetoxymethyl and Rs is C1-C3 alkyl; are useful analgesic agents. These compounds of formula I are prepared by deblocking the correspondingly blocked tetrapeptide offormula I.
                            式中的化合物
及其药学上可接受的无毒酸加成盐,其中 L 和 D 定义手性;
R 是氢或 C1-C3 伯烷基;
R2 是 C1-C4 伯烷基或仲烷基、烯丙基、
环丙基甲基、C1-C2 羟烷基或-(
CH2)m-U-
CH3,其中 U 是-S-或
而 m 是 1 或 2;
R3 是
环丙基甲基或烯丙基;以及 Z 是
其中 R4 是氢、乙酰基或乙酰氧甲基,Rs 是 C1-C3 烷基;这些都是有用的镇痛剂。式 I 的这些化合物是通过解锁式 I 中相应的受阻四肽而制备的。