Opioid receptor agonist as well as preparation method and application thereof

The invention relates to an opioid receptor stimulant and a preparation method and application thereof, and provides an oxaspiro small molecule compound, a pharmaceutical composition containing the compound and application of the oxaspiro small molecule compound as a therapeutic agent, especially as an MOR receptor stimulant and in preparation of drugs for treating and/or preventing related diseases such as pain. The MOR receptor stimulant with a novel structure, provided by the invention, shows high activity and has relatively high selectivity to MOR, and the maximum efficacy Emax of the MOR receptor stimulant is also obviously improved. 本发明为阿片受体激动剂及其制备方法和用途，提供了一类氧杂螺环类小分子化合物，以及含有该化合物的药物组合物及其作为治疗剂，特别是作为MOR受体激动剂和在制备治疗和/或预防疼痛等相关疾病的药物中的用途。本发明提供的一种结构新颖的MOR受体激动剂，表现出高活性，以及对MOR具有较高的选择性，并且其最大效能Emax也具有明显改善。