Development of Asymmetric Selenoxide and Telluroxide Elimination.

We%20succeeded%20in%20asymmetric%20selenoxide%20elimination%20leading%20to%20chiral%20allenic%20sulfones%20and%20chiral%20alkyl%20and%20aryl%20cyclohexylidenemethyl%20ketones%20by%20oxidation%20of%20the%20corresponding%20selenides%20with%20chiral%20oxidants%20such%20as%20Sharpless%20oxidant%20and%20Davis%20oxidant.%20In%20the%20former%20case%20the%20maximum%20enatioselectivity%20was%2042%ee，%20while%20in%20the%20latter%20case%20it%20reached%20to%2083%ee.%20The%20nature%20of%20alkyl%20or%20aryl%20group%20of%20RSe%20or%20ArSe%20moiety%20had%20a%20remarkable%20effect%20on%20the%20ee%20value.%20On%20the%20other%20hand，%20we%20have%20not%20yet%20succeeded%20in%20asymmetric%20telluroxide%20elimination.%20In%20connection%20to%20these%20asymmetric%20reactions%20we%20were%20also%20successful%20in%20catalytic%20asymmetric%20oxidation%20of%20sulfides%20to%20sulfoxides%20with%20t-BuOOH%20using%20binaphthol%20as%20a%20chiral%20auxiliary%20and%20kinetic%20resolution%20of%20sulfoxides%20catalyzed%20by%20chiral%20titanium-binaphtholcomplex.%20Furthermore，%20we%20found%20that%20the%20Sharpless%20oxidation%20of%20some%20aryl%20cinnamyl%20selenides%20afforded%20a%20chiral%201-pheny1-2-propen-1-ol%20via%20asymmetric%5B2，3%5Dsigmatropic%20rearrangement%20in%20a%20moderate%20to%20high%20selectivity(up%20to%2092%ee).

We succeeded in asymmetric selenoxide elimination leading to chiral allenic sulfones and chiral alkyl and aryl cyclohexylidenemethyl ketones by oxidation of the corresponding selenides with chiral oxidants such as Sharpless oxidant and Davis oxidant. In the former case the maximum enatioselectivity was 42%ee, while in the latter case it reached to 83%ee. The nature of alkyl or aryl group of RSe or ArSe moiety had a remarkable effect on the ee value. On the other hand, we have not yet succeeded in asymmetric telluroxide elimination. In connection to these asymmetric reactions we were also successful in catalytic asymmetric oxidation of sulfides to sulfoxides with t-BuOOH using binaphthol as a chiral auxiliary and kinetic resolution of sulfoxides catalyzed by chiral titanium-binaphtholcomplex. Furthermore, we found that the Sharpless oxidation of some aryl cinnamyl selenides afforded a chiral 1-pheny1-2-propen-1-ol via asymmetric[2,3]sigmatropic rearrangement in a moderate to high selectivity(up to 92%ee).