Phenethylamine

Phenethylamine (1-amino-2-phenylethane) is a monoamine compound that is widespread in nature, even found in chocolate, but as well as the human brain where it is discussed as a putative neuromodulator or neurotransmitter. Some consider phenethylamine to have psychoactive effects, however, it quickly metabolized by the enzyme MAO so that significant concentrations do not reach the brain. It is structurally related to the amino acids phenylalanine and tyrosine.

Substitutions to the phenethylamine molecule give rise to a group of compounds collectively known as phenethylamines. The term amphetamines is used to refer to the subset of phenethylamines that can be derived from substitution to amphetamine (α-methylphenethylamine), while those that derive from tyrosine are called catecholamines. Phenethylamines are widespread in nature as hormones, neurotransmitters and alkaloids. Examples of fundamental importance in the human nervous system are dopamine, epinephrine (adrenaline) and norepinephrine (noradrenaline). Plant alkaloids related to phenethylamine include the psychedelic drug mescaline, and the stimulants ephedrine and cathinone. Many synthetic phenethylamines have been investigated for their psychoactive effects, which are generally stimulant, empathogenic and/or psychedelic in nature. The most commonly used synthetic phenethylamines are amphetamine (speed, Benzedrine), methamphetamine (meth, ice) and MDMA (Ecstasy). A phenethylamine backbone can also be identified in the more complex structure of LSD. Some of the more important phenethylamines are tabulated below according to their structure. For simplicity the stereochemistry of these compounds is not covered in the table. Hundreds of other synthetic phenethylamines are known. This is due in large part to the pioneering work of Alexander Shulgin, much of which is described in the book PiHKAL.

Substituted phenethylamines, tabulated by structure

Short Name	α	β	R2	R3	R4	R5	N1	Full Name
tyramine					OH			4-hydroxyphenethylamine
dopamine				OH	OH			3,4-dihydroxyphenethylamine
epinephrine		OH		OH	OH		CH3	β,3,4-trihydroxy-N-methylphenethylamine
norepinephrine		OH		OH	OH			β,3,4-trihydroxyphenethylamine
salbutamol		OH			OH	CH2CH2OH	C(CH3)3	α1[tert-butylamino)methyl]-4-hydroxy-m-xylene-α1,α3'-diol
amphetamine	CH3							α-methylphenethylamine
methamphetamine	CH3						CH3	N-methylamphetamine
ephedrine	CH3	OH					CH3	N-methyl-β-hydroxyamphetamine
cathine	CH3	OH						β-hydroxyamphetamine
cathinone	CH3	=O						β-ketoamphetamine
methcathinone	CH3	=O					CH3	N-methyl-β-ketoamphetamine
bupropion	CH3	=O		Cl			C(CH3)3	3-chloro-N-tert-butyl-β-ketoamphetamine
fenfluramine	CH3			CF3			CH2CH3	3-trifluoromethyl-N-ethylamphetamine
phentermine	CH3,CH3							α,α-dimethylphenethylamine
mescaline				OCH3	OCH3	OCH3		3,4,5-trimethoxyphenethylamine
MDA	CH3			-O-CH2-O-				3,4-methylenedioxyamphetamine
MDMA	CH3			-O-CH2-O-			CH3	3,4-methylenedioxy-N-methylamphetamine
DOM	CH3		OCH3		CH3	OCH3		2,5-dimethoxy-4-methylamphetamine
DOB	CH3		OCH3		Br	OCH3		2,5-dimethoxy-4-bromoamphetamine
2C-B			OCH3		Br	OCH3		2,5-dimethoxy-4-bromophenethylamine
2C-C			OCH3		Cl	OCH3		2,5-dimethoxy-4-chlorophenethylamine
2C-I			OCH3		I	OCH3		2,5-dimethoxy-4-iodophenethylamine
2C-D			OCH3		CH3	OCH3		2,5-dimethoxy-4-methylphenethylamine
2C-E			OCH3		CH2CH3	OCH3		2,5-dimethoxy-4-ethylphenethylamine
2C-T-2			OCH3		SCH2CH3	OCH3		2,5-dimethoxy-4-ethylthiophenethylamine
2C-T-7			OCH3		SCH2CH2CH3	OCH3		2,5-dimethoxy-4-propylthiophenethylamine
2C-T-21			OCH3		FSCH2CH2CH3	OCH3		2,5-dimethoxy-4-(2-fluoroethylthio)phenethylamine

See also

• catecholamines
• PiHKAL
• Alexander Shulgin

• Book II of PiHKAL online
• Review and summary of PiHKAL, including table of 300+ phenethylamines: ascii postscript
• A Structural Tour of PiHKAL