Phytenic acid

This class of fatty acids has the general formula of R-(CH2CH-CH3CH2CH2) -CH-C = CH-COOH, where R = H. These saturated and partially unsaturated multibranched fatty acids belong to the is-oprenoid acid family, and in nature, isoprenoid acids are often found in microorganisms and plants. Phytenic acid, whose systematic name is 3,7,11,15-tetramethyl-2-hexadecenoic acid (Figure 4), is one member of this class. 

Figure 4 Phytenic acid, or 3,7,11,15-tetramethyl-2-hex-adecenoic acid.

It is not certain whether phytol is transformed to phytanic acid via the alpha-beta-unsaturated (phytenic) acid, or wether phytanic acid is formed by hydration of phytol to dihydrophytol and consecutive oxidation. The latter possibility seems to be more likely. While a small amount of phytenic acid was found in beta-... 

Approximately 5 000 naturally abundant acyclic and cyclic diterpenes derived from the parent hydrocarbon phytane are known The (3i ,7i ,ll )-enantiomer of phy-tane has been found in meteorites, oil slate, other sediments and, last but not least, in human liver. Oil slate additionally eontains (-)-(3if,7if,llif)-phytanoic acid which has also been isolated from butter. 1,3(20)-Phytadiene is one among many constituents of tobacco Nicotiana tabacum (Solanaceae) -1,3-phytadiene and its (%)-isomer are found in zooplankton. Chlorophyll in the chloroplasts of plant cells exemplifies an ester of +)-(lE,lR, l/ )-2-phyten-l-ol usually referred to as phytol. 2,6,10,14-Phytatetraene-l,19-diol, better known as plaunotol, is the ehief constituent of the leaves of flie Thai medicinal plant Croton sublyratus (Euphorbiaceae) used as "plau noi" or "kelnac" as an antiulcerative. 

Synthesis of 151 To a solution of salicylaldehyde 148 (116.4 mg, 0.6 mmol) and benzoic acid (22 mg, 0.18 mmol) in toluene (0.6mL) was added catalyst (/f)-150 (115.1 mg, 0.18mmol). The reaction mixture was stirred at room temperature for 5 minutes. Then, a solution of phytenal 149 (264 mg, 0.9mmol) in toluene (1.2mL) was added over 12 hours by using a syringe pump. The reaction mixture was stirred at room temperature for another 72 hours. The crude mixture was directly purified by flash chromatography (silica gel, hexane-/ethyl acetate 4 1 as the eluent) to give product 151 as a yellowish oil (170 mg, yield 58%, 97% ee). 

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