Analogs fatty acid methyl ester

Fatty alcohols may be separated and analysed by many of the procedures described in detail in Chapter 6 for fatty acid derivatives. For example, silver ion chromatography has been much used as an aid to the isolation and identification of specific components. Saturated and monoenoic fractions were isolated as the acetates from mullet roe by a column procedure [422], but TLC has been used more often hexane-diethyl ether (9 1, v/v) as the mobile phase in silver ion TLC will separate these fractions [344]. The effect of double bond position on the migration of all the isomeric c/s-octadecenols and the corresponding acetates on TLC with layers impregnated with silver nitrate was examined [327]. Like the methyl ester derivatives of the analogous fatty acids, the Rf values of isomeric acetates fall on a sinusoidal curve with a minimum around the 5- and 6-isomers, but the free alcohols hardly show this effect. Similarly, HPLC in the reversed-phase mode has been employed for the isolation of fatty alcohols, such as the insect sex hormones, under conditions... 

We then focused on the synthesis of lipid A analogs which contain 3-hydroxy fatty acids. For this purpose, sufficient amount of (R)-3-hydroxytetradecanoic acid ( ), which is the commonest hydroxy acid in Salmonella lipid A, was first prepared by means of an asymmetric reduction of the corresponding keto ester, i. ., methyl 3-oxotetradecanoate (j ) (7). Catalytic hydrogenation of 21 in the presence of Raney Ni modified with (R, R)-tartaric acid foaBr (8) afforded the crude (R)-ester in 85% enantiomeric excess. After saponification, the resultant acid was purified through its dicyclohexylammonium salt to give the optically and chemically pure (R)-acid In a yield of 61% from... 

Magnesium or lithium enolates of thiol carboxylic esters can be acylated with suitable reagents (c/ Volume 2, Part 1). Highly functionalized new derivatives are obtained. The example shown in equation (35)33,102 J5 closely related to the C-acylation of malonyl-CoA with acetyl-CoA, which plays an important role in the biosynthesis of polypeptides and fatty acids. (S)-4-Hydroxy-5-methyl-3-oxo-hexanoyl-L-leucine esters (41), 2-demethyl analogs of the Hip-Leu moiety of didemnin antibiotics, can be prepared via the 3-keto thiol carboxylic esters (40 equation 36). ° ... 

The synthesis of a novel cyclopropyl analog of arachidonic acid [7] via a convergent synthesis that employed methyl (lR,25)-2-formylcyclopropane-carboxylate in conjunction with the ylide from (3Z,6Z)-pentadeca-3,6-dienyl(triphenyl)-phosphonium iodide was reported (62). A new approach to cyclopropene fatty acids has been developed for the synthesis of methyl sterculate [8] and methyl 2-hydroxy-sterculate this involves the 1,2-deiodination of 1,2-diiodocyclopropanes with butyllithium at low temperature (63). The synthesis of deuterated cyclopropene fatty esters structurally related to palmitic and myristic acids has been reported (64). 

While sapwood contains very little sterol in the ester form (traces to 0.15 moles/g, dry weight basis), the amount rises strongly to about 1.1 moles/g in the inner heartwood (37, 38). Holl and Pieczonka (38) found the acid component of the esters in both cases was comprised of a number of fatty acids. In terms of the usual nomenclature (chain length number of double bonds), the fatty acid composition of the steryl esters in spruce heartwood was found to be 12 0 (10%), 14 0(12%), 16 0(20%), 16 1 (12%), 18 0(14%), 18 1 (16%), 18 2(5%), and unidentified (11%). The composition varied only slightly from this in sapwood. In both sapwood and heartwood of the spruce, the ester was a minor form of the total sterol. The ester to free sterol ratio was about 1 2 in the inner heartwood (37). Sitosterol and other sterols have also been found to exist partly in the ester form in the heartwood of angiosperms - e.g., the slippery elm (Ulmus rubra) (24). Similarly, the sterols in the bark of the western white pine (Pinus monticola) are partly (60%) esterified (13). In both heartwood and bark the steryl composition of the ester fraction approximately reflected the composition of the free sterol fraction in that sitosterol was the major component followed by its 24-methyl analogs (13, 37). A similar situation has been observed with non-woody angiosperms - e.g., Zea mays (71). 

A one-stage procedure involving sodium catalysed transesterification between raffinose undeca-acetate and methyl esters of long-chain fatty acids (derived, for example, from salad oil) has been employed to produce raffinose fatty acid polyesters in excellent yields (>96%) their physical properties are described as similar to those of analogous sucrose polyesters." Certain carbohydrate esters of fatty acids, e.a.. sucrose mono-laurate, -palmitate, and -stearate, have been found to enhance the activity of thiabendazole, a fungicide used against Penicillium dioitatum infections of citrus fruit. The mechanism of this action remains to be clarified. ... 

The reaction of triacylglycerols with alcohol is called alcoholysis. It can be catalysed by acids (sulfuric acid or 4-toluenesulfonic acid), and then an interesterification reaction, which is a parallel reaction to esterification of free fatty acids occurring in the fat. Alcoholysis is kinetically similar to esterification. The base catalysed reaction employs methoxides, hydroxides and carbonates of alkali metals. The most commonly used catalysts are sodium methoxide, sodium hydroxide or potassium hydroxide. Industrially produced alcoholysis products are methyl, ethyl or propyl esters (Figure 3.82) of fatty acids. Analogous to hydrolysis, mixing of fat (oil) with alcohol gives a two-phase system... 

These are analogs of previously described quaternaries that contain ester linkages to speed biodegradation (6). The most common are fatty acid esters of triethanolamine, quatemized with dimethyl sulfate or methyl chloride. They are mixtures of quatemized mono-, di-, and triesters. 

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