Methadone, structure forms

A comparable reaction was seen decades ago in the metabolism of methadone [173 - 175]. This well-known synthetic opiate undergoes A-demeth-ylation as a major metabolic reaction in humans and laboratory animals. The resulting secondary amine (11.168, Fig. 11.21) has never been isolated, as it undergoes practically instantaneous cyclization. The reaction is believed to proceed via the carbinolamine with formation of metabolite 11.169 as the major urinary metabolite in humans. This structurally intriguing basic compound is, in its neutral form, a pyrrolidine with an exocyclic C=C bond,... 

Morphine was known to the Sumerians and Egyptians as a very valuable pain killer in medicine it is also a powerful narcotic that is habit forming. A great deal of effort has been spent in finding a derivative of morphine that has its good properties, and less of its bad properties. Then, in 1944, demerol and methadone were discovered, which are even more powerful than morphine, but bear no structural relation to morphine. The leading theory now is that both morphine and methadone have the same T-shape, and may fit the receptor. 

Fig. 8.2 Two-dimensional structures of l-methadone and the enol tautomer of l-methadone together with three-dimensional space-filling baU-and-stick (la, c and 2a, c) and CPK models (lb, d and 2b, d) for l-methadone and its enol tautomer, respectively. The models of l-methadone show one of many possible conformations while the models of the enol form show the molecule locked by the intramolecular...

---