The analogue of phenethylamine with the ethylamine side chain shortened by one carbon atom to instead be a methylamine chain is benzylamine (phenylmethylamine).[3] In contrast to phenethylamine and phenylpropylamine, benzylamine is said to be inactive as a norepinephrine releasing agent (NRA).[3] However, certain derivatives of benzylamine have nonetheless been found to show MRA-like effects in animals.[4][5] In addition, benzylpiperazine, an analogue of benzylamine with a methylamine-like side chain, is a potent MRA and psychostimulant.[6][2][7]
Monoamine release of phenylpropylamine and related agents (EC50Tooltip Half maximal effective concentration, nM)
12Biel JH, Bopp BA (1978). "Amphetamines: Structure-Activity Relationships". Stimulants. Boston, MA: Springer US. pp.1–39. doi:10.1007/978-1-4757-0510-2_1. ISBN978-1-4757-0512-6. The β-phenethylamine skeleton is a critical feature of the molecule since either increasing or decreasing the number of carbons between the phenyl ring and the nitrogen reduced or abolished the activity. Both the γ-phenylpropylamines (e.g., 1-phenyl-3-aminobutane, γ-phenylpropylamine, γ-phenyl-N,N-dimethylpropylamine) and the benzylamines (e.g., α-methylbenzylamine, N,N-diethylbenzylamine, benzylamine) were found to be inactive as releasers of norepinephrine (Daly et al., 1966).
