 Cyclopentamine is the cyclopentane homolog of propylhexedrine, differing only in terms of the contracted ring size of a cyclopentane, containing one —CH2— unit less than the cyclohexyl group.In terms of the acyclic part of the molecule, both cyclopentamine and propylhexedrine are the same as methamphetamine, all three molecules containing the 2-methylaminopropyl side-chain.The difference between them is that whereas methamphetamine is an aromatic molecule containing a phenyl group, cyclopentamine and propylhexedrine are entirely aliphatic and contain no delocalized electrons at all.