Phenylpropane compounds

There has been little scientific evaluation of aromatherapy oils but it is known that the terpenoid and phenylpropane compounds found in essential oils do possess biological activities ranging from antibacterial, antiinflammatory, sedative etc. There is evidence that molecules such as terpenoid hydrocarbons, esters etc. can be absorbed transdermally into the blood-stream. In addition, the massage element involving physical manipulation of strained tissues as well as the psychological effects of touch and of the smell of the oil, is of significance. Some trials of aromatherapy have shown benefits in intensive-care patients, in epilepsy and in endometriosis. The most popular oils are listed below with their claimed uses. 

Thus cumene [98-82-8] (1-methylethylbenzene, 2-phenylpropane, isopropylbenzene), is a substituted aromatic compound ia the benzene (qv),... 

Addition of metalated, enantiomerically pure a-sulfinyl dimethylhydrazones (e.g., 9) to racemic a-chiral aldehydes 10 proceeds with good to excellent diastereo- and enantioselectivi-ty12. Diastereomeric ratios increase with increasing steric demand of the acetaldehyde substituent R1 compared to the methyl group, and each diastereomer is obtained with high enantiomeric excess. In the aldol-lype addition to 2-phenylpropanal, one of the four possible stereoisomers is formed selectively. The relative (syn) and absolute (R.R) configuration is in accord with Cram s and related rules as well as H-NMR data of closely related compounds. 

Hydroxyphenylpyruvic acid plays an important role in the biogenesis of compounds with a phenylpropane skeleton, and it has been used as substrate in several enzyme studies. Published procedures for its preparation are unsatisfactory in many ways. The alkaline hydrolysis of the azlactone of a-bcnzoylamino- -acetoxycinnamic acid 7 makes necessary a tedious separation of the resulting benzoic acid, and the yield is only 34% based on -hydroxybenzaldehyde. The hydrolysis of 5- ( -hydroxybenzal)-3-phenylhydantoin 9 requires a separation of phenylurea. Finally, the two-step cleavage of the azlactone of a-acetamino- -acetoxycinnamic acid 8 does not proceed easily, and impure products are obtained. In applying this procedure to the synthesis of a carboxyl-labeled -hydroxyphenylpyruvic acid, the overall yield was only 9%.u It must be kept in mind that any prolonged isolation procedure will cause some decomposition of this sensitive compound. 

Lignin may be defined as the incrusting material of the plant which is built up mainly, if not entirely, of phenylpropane building stones it carries the major part of the methoxyl content of the wood it is unhydrolyzable by acids readily oxidizable, soluble in hot alkali and bisulfite, and readily condenses with phenols and thio compounds (14). 

A number of compounds containing nitroso or coordinated nitrosyl groups exhibit instability under appropriate conditions. Individually indexed compounds are Ammonium /V-nitrosophcnvlaminooxidc. 2399 A-(2-Chlorocthyl)-A-nitrosocarbamoyl azide, 1131 1 -Chloro-1 -nitrosocyclohexane, 2419 2-Chloro-1 -nitroso-2-phenylpropane, 3147... 

The structural elements can be assembled in only one way and this identifies the compound as 1-bromo-3 -phenylpropane. 

Phomopsis sp. strain endophytes of the medicinal plant Erythrina crista-galli continue to yield novel compounds (Table 1). New phenyl-propane, pyronol, benzoic acid, phenylpyran, macrocyclic, and alkene compounds were discovered, as well as the known compounds clavatol, 4-hydroxymellein, mellein, mevalonolactone, mevinic acid, nectriapyrone, phomol, scytalone, and tyrosol. The new compounds were phomopy-ronol (101), 3-phenylpropane-l,2-diol (102), 4-(2,3-dihydroxypropoxy) benzoic acid (103), 2-(hydroxymethyl)-3-propylphenol (104), 2-... 

The bioreduction of carbonyl compounds with reductases has been exploited for many years, especially in the case of ketones, with baker s yeast Saccharomyces cerevisiae) being the most popular biocatalyst [45]. For instance, yeast treatment of 3-chloropropiophenone affords the expected (lS)-3-chloro-l-phenylpropan-l-ol, which was treated with trifluorocresol in tertrahydrofuran in the presence of tri-phenylphosphine and diethyl azodicarboxylate at room temperature to give (3R)-l-chloro-3-phenyl-3-[4-(trifluoromethyl)phenoxy]propane and the later reaction with methylamine leads to (R)-fluoxetine that is an important serotonin uptake inhibitor (Scheme 10.19) [46]. 

Phenylpropanes are aromatic compounds with a propyl side chain attached to the benzene ring, which can be derived directly from phenylalanine. Naturally occurring phenylpropanoids often contain oxygenated substituents, e.g. OH, OMe or methylenedioxy, on the benzene ring. Phenylpropanoids with hydroxyl substituent(s) on the benzene ring belongs to the group of phenolics, e.g. caffeic acid and coumaric acid. 

Hypericum perforatum (Clusiaceae), commonly known as SJW, is used in many countries for the treatment of mild-to-moderate forms of depression. Several clinical studies provide evidence that SJW is as effective as conventional synthetic antidepressants (46-51). From a phytochemical point of view, H. perforatum belongs to one of the best-investigated medicinal plants. A series of bioactive compounds have been detected in the crude material, namely phenylpropanes, flavonol derivatives, biflavones, proanthocyani-dins, xanthones, phloroglucinols, some amino acids, naphthodianthrones, and essential oil constituents (Fig. 3) (52-54). 

To a solution of 2 (40.9 g, 0.1 mol) in anhyd CH2C12 (100 mL) was added 3-phenylpropan-1-ol (3 8.2 g, 0.06 mol) dropwise (maximum temperature 60 C exothermic reaction). Once the addition was complete, the reaction was stirred at 50 C for a further 5 h, then poured over ice and extracted with CII2CI2. The combined organic layers were dried (MgS04) and evaporated tinder reduced pressure and the residue distilled to give the title compound yield 42 g (62%) bp 81 C/45.6Torr. 

The hexahydropyrimidine (58), formed from l-phenylpropane-l,2-dione and propane-1,3-diamine, is an excellent precursor for the a-diimine macrocyclic complexes (60), presumably via the amino ketone (59) (Scheme 36).126 In this case, intramolecular cyclization of (59) to (58) is reversible, so that the metal ion can exert a thermodynamic template effect in formation of the complex (60). This represents a further example of a long-known phenomenon in which a metal ion can stabilize an a-diimine structure by virtue of the formation of stable five-membered chelate rings. Many 2-hydroxy- or 2-mercapto-amines undergo reaction with a-dicarbonyl compounds to yield heterocyclic compounds rather than a-diimines. However, in the presence of suitable metal... 

Hydratropa aldehyde racemizes quickly even at room temperature (8). No reliable data have been found in the literature on the correlation between optical purity and rotatory power for this compound. We have estimated for the optically pure (R) -hydratropa aldehyde, [< ]D25 —238° (maximum value), by correlation to ( + )(R)-hydratropa alcohol via ( —) (R) -l-ethoxy-2-phenylpropane (9). 

Hydrolytic fission of a carbon chain which occurs with a,a,a-trihalo carbonyl compounds and which affords haloforms is observed with certain fluorinated compounds. Although R3C —F bonds are not broken, it is convenient to mention the process here. A special example is the hydrolysis of hexafluoro-2-phenylpropan-2-ol (5) in which two moles of trifluoromethane are liberated. 73... 

The elimination of the hydridopalladium group to the allylic position causes the formation of 3-substituted carbonyl compounds when allylic alcohols are reacted with organic halides (39). For example, when iodobenzene is reacted with methallyl alcohol, 2-methyl-3-phenylpropanal was formed in 91% yield along with 4% of 2-methyl-2-phenylpropanal ... 

For example, both cis- and with bromine in acetic acid in the ratios indicated in Equation 7.16.32 Note that in both these compounds anti addition still predominates, and that an equilibrium mixture of syn and anti adduct is not obtained. The results cited in Table 7.5 show that if the ft r.arhnn is made even more able to stabilize a positive charge, the amount nf anti addition decreases... 

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