| 摘要 |
Analgesic compounds are of the general formula (I): <SEE FIG.1> in which, R 1 and R 2 each represents hydrogen or C1-C6 alkyl, or R 1 and R 2 together with the nitrogen atom to which they are attached form a heterocycle: E represents methylene, sulphur, oxygen or imino group optionally substituted with C1-C6 alkyl or aralkyl; ring A is aryl or heteroacyl ring, optionally substituted; R 3 is hydrogen or C1-C6 alkyl and R 4 is hydrogen or R 3 and R 4 together represent a group of formula (IV): -(CR a R a)m-C(=Y)- (IV) (wherein R a and R a is C1-C6 alkyl or hydrogen, up to a maximum of 3 alkyl groups, m is 1, 2, or 3, and Y is two hydrogens or oxygen); provided that when E represents a methylene group, then R 3 is a C1-C6 alkyl group or R 3 and R 4 together represent a group of the formula (IV).
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