<unk>  is an opiate analogue that is the N-demethylated derivative of morphine.<unk>  has relatively little opioid activity in its own right, but is a useful intermediate which can be used to produce both opioid antagonists such as nalorphine, and also potent opioid agonists such as N-phenethylnormorphine. It is also produced as a major metabolite of morphine, with its formation from morphine catalysed by the liver enzymes CYP3A4 and CYP2C8.
Normorphine
Nalorphine
Morphine 
Codeine
Fentanyl 
Dihydrodesoxymorphine
Meperidine 
Morpholine