The analgesic activity of compounds and pharmaceutical use

The compound or a pharmaceutically acceptable salt thereof The present invention relates to the structure shown in formula I has more potent analgesic activity and low toxicity, containing these compounds as active ingredients of the pharmaceutical composition, and a pharmaceutically acceptable derivative thereof acceptable salt thereof, for the preparation of analgesic medicament. Formula I, R is a hydrogen atom or a C1-C5 linear or branched alkyl group alkyl, n is 0 or an integer of 1-3, with the configuration of the carbon atom attached to R is R type or S type.