P-Phenylethylamine

P-Phenylethylamine is conveniently prepared by the hydrogenation under pressure of benzyl cyanide with Raney nickel catalyst (see Section VI,5) in the presence of either a saturated solution of dry ammonia in anhydrous methyl alcohol or of liquid ammonia the latter are added to suppress the formation of the secondary amine, di- P phenylethylamine ... 

P-Phenylethylamine. Prepare p-phenylethyl phthalimide as above by substituting P phenylethyl bromide (Section 111,37) for benzyl... 

It is of interest to note that reduction of p-nitrostyrene with lithium aluminium hydride (compare Section VI, 10) gives p-phenylethylamine CgHgCHjCHjNHj. 

An example of the application of the Raney nickel catalyst is given in Section IV,35 (p-phenylethylamine from benzyl cyanide). 

MAO is known to occur in at least two forms, MAO A and MAO B, based on substrate selectivity, inhibition by various dmgs, and cloning experiments. Clorgyline [17780-72-2] is a specific inhibitor of MAO A, which displays a substrate specificity for NE and serotonin. Deprenyl [2323-36-6] is a selective inhibitor of MAO B, and displays a substrate preference for P-phenylethylamine and benzyl amine. Dopamine and tyramine are substrates for both enzymes. 

The isoquinoline framwork is derived from the corresponding acyl derivatives of P-hydroxy-P phenylethylamines. Upon exposure to a dehydrating agent such as phosphorous pentaoxide, or phosphorous oxychloride, under reflux conditions and in an inert solvent such as decalin, isoquinoline frameworks are formed. 

In essence, what was happening was that the CSL supplied P phenylethylamine. This had been produced from the amino add phenylalanine by the action of the microflora in the CSL. Thus ... 

The obvious way is to indude p-phenylacetic add or p-phenylethylamine in cultures. Indeed, when (J-phenylacetic add was added to cultures grown in CSL, the yields of penidllin were enhanced further. Typical yields were 100-150 ig ml 1. 

Besides tryptamine 2-526, tryptophan and 3,4-dimethoxy-P-phenylethylamine were also used. The latter led to a tetrahydroisoquinaline, but the yields were much lower. 

Baker GB, Rao TS, Coutts RT. 1986a. Electron-capture gas chromatographic analysis of p-phenylethylamine in tissues and body fluids using pentafluorobenzenesulfonyl chloride for derivatization. J Chromatogr Biomed Appl 381 211. 

Tryptamine Histamine Cadaverine Putrescine p-phenylethylamine Tyramine... 

Biogenic amines are commonly found in fermented meats. Histamine poisoning has not been associated with this type of product, however histamine has been found at low levels in some fermented meats (Dierick et al., 1974 Taylor et al., 1978 Vidal et al., 1990 Shalaby, 1993 Maijala et al., 1993). The most common amine found in fermented meats is tyramine (Trevino et al., 1997 Eerola et al., 1998), which is found at higher concentrations than other amines. The toxic level of biogenic amines is 100 mg per 100 g of product (Arnold et al., 1978). Taylor et al. (1978) and Vandekerckhove (1977) found amounts of histamine up to 55 mg per 100 g, putrescine up to 40 mg per 100 g, cadaverine up to 5.6 mg per 100 g, tyramine up to 151 mg per 100 g, and p-phenylethylamine up to 6.1 mg per 100 g in dry sausage. Table 6.9 lists the... 

This method is very useful for the construction of 1-substituted 3,4-dihydroisoquinolines, which if necessary can be oxidized to isoquinolines. A P-phenylethylamine (l-amino-2-phenylethane) is the starting material, and this is usually preformed by reacting an aromatic aldehyde with nitromethane in the presence of sodium methoxide, and allowing the adduct to eliminate methanol and give a P-nitrostyrene (l-nitro-2-phenylethene) (Scheme 3.17). This product is then reduced to the p-phenylethylamine, commonly by the action of lithium aluminium hydride. Once prepared, the p-phenylethylamine is reacted with an acyl chloride and a base to give the corresponding amide (R = H) and then this is cyclized to a 3,4-dihydro-isoquinoline by treatment with either phosphorus pentoxide or phosphorus oxychloride (Scheme 3.18). Finally, aromatization is accomplished by heating the 3,4-dihydroisoquinoline over palladium on charcoal. 

Alternatively, a P-methoxy-P-phenylethylamine can be used to circumvent the oxidation step after the conventional Bischler-Naperialski cyclization. Here, when treated with the phosphorus reagent the amide (R = OMe) undergoes both cyclization and the elimination of methanol to give the isoquinoline (R = H) directly. This is known as the Pictet-Gams modification of the Bischler-Napieralski synthesis. 

Newer MAOI drugs are selective for the MAO-A subtype of the enzyme, and are less likely to interact with foods or other drugs. Monoamine oxidase (MAO) inactivates monoamine substances, many of which are, or are related to, neurotransmitters. The central nervous system mainly contains MAO-A, whose substrates are adrenaline (epinephrine), noradrenaline (norepinephrine), metanephrine, and 5-hydroxyti7ptamine (5-HT), whereas extra-neuronal tissues, such as the liver, lung, and kidney, contain mainly MAO-B which metabolises p-phenylethylamine, phenylethanolamine, o-tyramine, and benzylamine. 

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