Selenium-based oxidizing agent

The selective oxidation of secondary alcohols which contain either a sulfide or selenide is also possible using either selenium-based oxidizing agents (equations 39 and 40), or with a modified Oppe-nauer system involving trichloroacetaldehyde (equation 41). ... 

As well as thiol esters, selenol esters (1) frequently exhibit a high and selective reactivity toward nucleophiles, which is enhanced even further by activation with heavy ions or oxidizing agents. These properties make selenol esters valuable acyl transfer agents. This review deals with general methods for the synthesis of selenol esters and their reactivity as acyl transfer agents. Furthermore, selenoesters (2), isomeric compounds of selenol esters, and their derivatives selenoamides (3) are also described. These compounds show the characteristic reactivity based on the carbon-selenium double bond. 

Metal [258], metalloid [259], and nonmetal [260] -based oxidants are very efficient but rather toxic agents thus, vanadium oxytrichloride [258f], 2,6-dicarboxypyridinum chlorochromate (DCPCC) [258a], bis(trimethylsilyl) chromate (BTSC) [258e], chromic acid [261], and selenium... 

Epoxldation of (12) with a nucleophilic agent occurred only from the outside of the molecule and the necessary oxidation to (7) could be carried out with RuC and NalO. The remaining steps required new reactions based on selenium chemistry and gave methylenomycin in 12% overall yield from maleic anhydride. 

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