Provided are compounds of the formula: R1; R2, R3; R4; A; X; Y and Z are defined in the present disclosure; pharmaceutically acceptable salts thereof, deuterium forms thereof, isomers thereof, and mixture thereof; and processes for their preparation. The compounds can be used for treating a patient suffering from a condition that is capable of treatment with an agonist and/or antagonist of the opioid receptors and are especially useful a patient suffering from pain, treating a patient in need of an immunosuppressant to prevent rejection in organ transplant and skin graft, in need of an anti-allergic agent, in need of an anti-inflammatory agent, in need of a brain cell protectant, for drug and/or alcohol abuse, to decrease gastric secretion, for diarrhea, for cardiovascular disease, for a respiratory disease, in need of a cough and/or respiratory depressant, for mental illness, for epileptic seizures and other neurologic disorders.