Triene conjugate

This method has been used extensively for the generation of diene- and triene-conjugated nitrile ylides (see Section 7.4.1.2) using strong bases. Potasium tert-butoxide (58) was used for the most part but in recent work (59,60) it was reported that lithium bisftrimethylsilyl)amide is both more effective and more convenient. It has also been shown that thermally unstable imidoyl chlorides for use in these reactions can be prepared by reaction of the corresponding amides with chlorodi-methylformiminium chloride at 0 °C, a reaction that is more effective than using either thionyl chloride or phosphoms pentachloride at higher temperatures (61). 

When the conjugation is further extended, as in the triene-conjugated nitrile ylides (347), it is interesting that 1,1-cycloaddition still appears to be the favored primary process. In the case of the cis isomers 347 [R R =Me, Ph or (CH2)3 R = Ph, Me, C02Me] the proximate products (348) were not isolated but rearranged spontaneously via an aza-Cope process to give the bridged isoquinolines (349) in moderate yield (20-65%) (60,206). 

It is rare that a year passes without a report on the cyclisation of triene-conjugated nitrile ylides from Sharp and co-workers, and this year is no exception. In this example. 

Transesterification, fatty acid analysis of lipids, 437, 439 Triacetin, lipase assays, 378 Triacylglycerol acylhydrolase, 371, 375, 378. See also Lipases Triacylglycerols, 432 Tributyrin, lipase assays, 378 Trichloroacetic acid (TCA) solubility index for protein hydrolysis, 152 in TBARS determination, 548-550 Trienes, conjugated, determination of, 515-517, 523-524, 526, 528 Trifluoroacetic acid (TFA), for determination of neutral sugars, 721-722, 724-725, 729-730... 

The UV method is based on measurements of extinction or optical density in the 232 nm and 270 nm regions in which diene and triene conjugated systems are known to absorb UV. The intensity of the UV spectral absorption band at 232 nm and 270 nm is also useful to detect, and also in part to quantify, both the extent of the oxidation of monounsaturated and polyunsaturated acid moieties... 

Thermal decomposition of the sodium salts of tosylhydrazones 45a-e gave the triene-conjugated diazo 46a-e, which have a,(3 aromatic and 7, e,C olefinic unsaturation. Such diazo compounds react at 25 °C via an intramolecular [3+2] cycloaddition with unprecedented regioselectivity to give the bridged benzodiazocine 6a-e. 

These were developed to impart some of the properties of tung oil to the non-conjugated oils, such as linseed or soybean oil. The processes involved treatment of those latter oils with catalysts such as nickel, alkali or alkali metal alkoxides to conjugate the double bonds. Products with up to 50% diene and 15% triene conjugation could be obtained. They resembled dehydrated castor oil more than tung oil in properties. None is used commercially to any extent at the present time. 

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