Textbook Problem

16-59 Morphine and its O-methylated derivative, codeine, are among the most effective painkillers known. However, they possess two serious drawbacks: they are addictive, and repeated use induces a tolerance to the drug.

Many morphine analogs have been prepared in an effort to find drugs that are equally effective as painkillers but that have less risk of physical dependence and potential abuse. Following are three of these.