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File:Trans-(±)-Cypenamine Enantiomers Structural Formulae.png
Systematic (IUPAC) name
CAS Number 15301-54-9
ATC code none
PubChem CID 21786
ChemSpider 20476
Chemical data
Formula C11H15N
Molar mass 161.2435 g/mol[[Script error: No such module "String".]]
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Cypenamine, or phenylcyclopentamine, is a stimulant drug. It is currently known only in scientific research and has never been developed for market use. The trans- isomer is reported to be more active than the racemate.[1] Cypenamine is currently legal throughout the entire world, and though its chemical structure has a vague similarity to certain controlled stimulants like fencamfamine (Glucoenergan, Reactivan), it is likely that it is too distant for it to be considered an illicit analogue under say the United States (U.S.) Federal Analogue Act (FAA) of the Controlled Substances Act (CSA).


2-Phenylcyclopentan-1-amine is a compound with two stereocenters. Thus, the following four following stereoisomers may exist:

  • (1R,2S)-trans-2-phenylcyclopentan-1-amine
  • (1S,2R)-trans-2-phenylcyclopentan-1-amine
  • (1R,2R)-cis-2-phenylcyclopentan-1-amine
  • (1S,2S)-cis-2-phenylcyclopentan-1-amine

The racemate (±)-trans-2-phenylcyclopentan-1-amine [1:1 mixture of (1R,2S)-trans-2-phenylcyclopentan-1-amine (box, left) and (1S,2R)-trans-2-phenylcyclopentan-1-amine (box, right)] is the active ingredient of cypenamine.[2] Furthermore, the kinetic resolution[disambiguation needed File:InterlanguageLinks-Asset-Pencil-Hover.gif] of (±)-trans-2-phenylcyclopentan-1-amine by lipase B from Candida antarctica may effectivily performed by an aminolysis reaction.[2]

Racemic cis-2-phenylcyclopentan-1-amine [1:1 mixture of (1R,2R)-cis-2-phenylcyclopentan-1-amine and (1S,2S)-cis-2-phenylcyclopentan-1-amine] has found no pharmacological application.


Cypenamine is an obvious homologue, containing an expanded alicyclic ring that is two -CH2- units larger than the highly strained/reactive cyclopropane of tranylcypromine. Based on this logic, one would have to contend that the cyclobutane[citation needed] homologue is yet another possibility. The cyclohexane homologue is known to have been reported, although the LD50's were all less than for plain amphetamine, it was still a functional stimulant.

See also


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  1. Burgos A, Kamenka JM, Rousseau B. Use of tritiated methylborane in the synthesis of labelled primary amines. Journal of Labelled Compounds and Radiopharmaceuticals. 1991; 29(12):1347-1350.
  2. 2.0 2.1 Javier González-Sabín, Vincente Gotor, and Francisca Rebolledo: Kinetic resolution of (±)-trans- und (±)-cis-phenylcyclopentanamine by CALB-catalyzed aminolysis of esters: the key role of the leaving group, Tetrahedron:Asymmetry 15 (2004) 481–488.