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Resolution with chiral Se reagent The chiral selenium compound shown (Tf = triflate) promotes kinetic resolution of racemic allylic alcohols in methanol, according to a study by chemists at the University of Perugia, in Italy. The reagent preferentially reacts with one enantiomer--adding across the double bond--leaving the unreacted allylic alcohol enantiomerically enriched [Org. Lett., published online Nov. 11, http://dx.doi.org/10.1021/ol048001+]. "To the best of our knowledge, this is the first example of a kinetic resolution process promoted by an organoselenium reagent," write the researchers, led by Marcello Tiecco. The kinetic resolution is not catalytic: Two equivalents of racemic allylic alcohol require one equivalent of the reagent. After column chromatography, the unreacted alcohol is recovered with enantiomeric excesses of 90 to 94%. Chemical treatment of the addition product with triflic acid releases the other enantiomer. The chiral selenium reagent is recovered as the diselenide. |
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