Phosphonium deuteriation

Elucidation of the physiological role of arachidonic acid 13 and other polyunsaturated fatty acids, particularly the role of all Z-4,7,10,13,16,19-decosahexaenoic acid 14, found in brain, required the corresponding stable-isotope labelled material1011. The deuteriated phosphonium salt 15, the key intermediate used in the synthesis of title compound 16 (equation 8), has been prepared in 19% overall yield12 starting with ethanol-D6 (equation 7). 

Band Assignment and Structural Elucidation.—The change in frequency of v(PH) from 2410 to 1753 cm upon deuteriation confirmed the presence of a PH bond in (121). In contrast to v(OH) of acidic and alcoholic OH groups, v(PH) of the phosphonium salt (121) is at higher wavenumber than v(PH) for primary and secondary phosphines ca. 2300 cm" ), and it is still... 

H-atoms in a-position of phosphonium salts can be easily replaced by deuterium under mildly basic conditions. The deuteriated phosphonium salts may serve as... 

Sulphonyl ylides usually are obtained by proton removal from a sulphone. Jarvis and Saukaitis" have found that the reaction of an a-bromo- or o-chloro-sulphone with triphenylphosphine resulted in abstraction of the halc en and formation of the sulphonyl ylide as an intermediate, which was trapped by protons from the water present. Benzyl phenyl sulphone was converted into the aa-dilithio-carbanion by treatment with n-butyl-lithium in THF-heptane," and Bosworth and M nus " have reported that a bicyclic phenylsulphone, upon treatment with n-butyl-lithium and then D2O, was converted into the ao-dideuteriosulphone, and that it was not possible to obtain the mono-deuteriosulphone by that method. Kaiser et al. have found that using sodium, lithium, or potassium amide with dimethyl sulphone or with dibenzyl sulphone resulted in formation of the aa -dicar-banion, as detected by deuteriation or by reaction with benzophenone. Amel and Marek determined the pK. s of a series of phenylphenacyl sulphones and concluded that the sulphone group provided less stabilization for the phenacylide than did a sulphonium group. The p value for substituents on the phenacyl portion was similar to that obtained for sulphonium, phosphonium, arsonium, and pyridinium phenacylides. 

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