The application is directed to compounds of Formula I-Aand pharmaceutically acceptable salts and solvates thereof, wherein , R1a, R2a, R3a, R4 and Za are defined as set forth in the specification. The invention is also directed to use of compounds of Formula I-A to treat disorders responsive to the modulation of one or more opioid receptors, or as synthetic intermediates. Certain compounds of the present invention are especially useful for treating pain.本案係關於式I-A化合物及其藥學上可接受之鹽類和溶劑合物，其中、R1a、R2a、R3a、R4和Za為如說明書中所定義者。本發明亦關於式I-A化合物於治療對一或多種類鴉片受體之調節有應答之失調症的用途或作為合成中間體之用途。本發明的某些化合物對治療疼痛特別有用。
