Nortriptyline is 5-(3-methylaminopropyliden)-10,11-dihydrodibenzcycloheptene (7.1.17). Nortriptyline differs from desipramine in the same manner in which amitriptyline differs from imipramine. In nortriptyline, the nitrogen atom in the central part of the tricyclic system of desipramine is replaced by a carbon atom, which is bound to a side chain by a double bond.
Two suggested methods of nortriptyline synthesis are based on the N-demethylation of amitriptyline. The third way utilizes the reaction of methylamine with 5-(3-bromopropyliden)-10,11-dihydro-5H-dibenz[a,d]cycloheptene (7.1.18).
According to the first scheme, demethylation takes place by the reaction of amitriptyline (7.1.4) with methyliodide, which leads to the formation of a quaternary ammonium salt (7.1.16), the reaction of which with methylamine at a relatively high temperature gives the desired nortriptyline (7.1.17) [25].
According to the third scheme, nortriptyline is synthesized by reacting methylamine with 5-(3-bromopropyliden)-10,11-dihydro-5H-dibenz[a,d]cycloheptene (7.1.6) [8].