Seleninate ester

Circular dichroism spectra were obtained of optically active seleninate esters 36 <2005JOC5020>. 

Reacting the cyclic seleninate ester 15 with an excess (three fold) of pentanethiol gave the selenenyl sulfide 104 (Equation 18) <2005JOC9237>. Treating 105 with benzyl thiol provided the selenenyl sulfide 106 via the intermediates depicted in Scheme 5 <2002JA12104>. 

Reaction of optically active seleninate ester (/ )-(—)-107 with methylmagnesium bromide gave the selenoxide (R)-(4-)-108 (Equation 19) <2005JOC5020>. 

Seleninate esters 36a and 36b were prepared from bromobenzyl alcohol derivatives 178 via selenides 179 (Scheme 11) <2005JOC5020>. Seleninate ester 36c was prepared from 2-(chloroseleno)benzoyl chloride 170 <2005JOC5020>. Compounds 36b and 36c were successfully subjected to optical resolution on a preparative scale,... 

The cyclic seleninate ester 105 exhibited remarkable glutathione peroxidase-like catalytic activity in a model system where fer7-butyl hydroperoxide was reduced with benzyl thiol to afford dibenzyl disulfide and tert-h xf alcohol <2003JA13455>. 

The selenenate 14 exhibited excellent glutathione peroxidase-like catalytic activity <2004AGE4513>. Compounds 15 and 16 were also investigated <2005JOC9237>. Both the seleninate ester and the spirocyclic compound were found to be more efficient catalysts than epselen. For other studies on Se-O and Te-O heterocycles, see <2005JOC9230>. 

In a reinvestigation of earlier work,64 Mock and McCausland established that the products of cycloaddition of dienes and selenium dioxide have six-membered ring seleninic ester structures [Eq. (40)].65... 

Cyclic seleninate esters have been implicated in catalytic cycles in which diselenides act as glutathione peroxidase mimetics <2003JA13455> (see Section 9.15.11). Treatment of the diselenides 48 and 49 with excess / -rt-butylbydro-peroxide leads to the formation of the first unsubstituted isolable cyclic seleninates 50 and 51 (Equations 9 and 10). The six-membered ring compound 50 proved to be a less effective catalyst than 51 in the former reactions. 

Diels-Alder reactions. Heldeweg and Hogeveen have shown that, at least in the case of highly reactive dienes, the initial products of cycloaddition of sulfur dioxide are sulfinic esters rather than sulfones. Thus reaction of the tricyclic diene (1) with SO2 at room temperature leads to the sulfinic ester (2). This ester is unstable thermally and rearranges mainly to the aromatic ester (3). They also point out the similarity between cycloaddition reactions of sulfur dioxide and selenium dioxide. Thus (1) reacts with the latter reagent to give the seleninic ester (4), probably formed via the intermediate (a). 

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