- Lewis Base-Catalyzed Enantioselective Conjugate Reduction of β,β-Disubstituted α,β-Unsaturated Ketones with Trichlorosilane: E/ Z-Isomerization, Regioselectivity, and Synthetic Applications
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The chiral bisphosphine dioxide-catalyzed asymmetric conjugate reduction of acyclic β,β-disubstituted α,β-unsaturated ketones with trichlorosilane affords saturated ketones having a stereogenic carbon center at the carbonyl β-position with high enantioselectivities. Because the E/Z-isomerizations of enone substrates occur concomitantly, reduction products with the same absolute configurations are obtained from either (E)- or (Z)-enones. Conjugate reduction is accelerated in the presence of an electron-rich aryl group at the β-position of the enone owing to its carbocation-stabilizing ability. Computational studies were also conducted in order to elucidate the origin of the observed enantioselectivity. The regio- and enantioselective reductions of dienones were realized and applied to the syntheses of ar-turmerone, turmeronol A, mutisianthol, and jungianol, which are optically active sesquiterpenes.
- Sugiura, Masaharu,Ashikari, Yasuhiko,Takahashi, Yuka,Yamaguchi, Koki,Kotani, Shunsuke,Nakajima, Makoto
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p. 11458 - 11473
(2019/10/11)
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- Me3SiCl-NaI-CH3CN AS AN EFFICIENT AND PRACTICAL REDUCING AGENT FOR BENZYLIC ALCOHOLS
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Secondary and tertiary benzylic alcohols are reduced conveniently to the corresponding aryl alkanes by using Me3SiCl-NaI-CH3CN reagent in hexane.The reaction was successfully applied to a short step synthesis of (+/-)-ar-turmerone.
- Sakai, Takashi,Miyata, Kazuyoshi,Utaka, Masanori,Takeda, Akira
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p. 3817 - 3818
(2007/10/02)
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- Synthesis of ar-Pseudotsugonoxide
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Carbethoxylation of p-methylacetophenone (II) with ethyl carbonate/NaH in anhyd. benzene-DMF mixture gives the β-ketoester (III) which on ketalization with ethylene glycol in the presence of catalytic amount of PTS in dry benzene provides ethyl 3,3-ethyle
- Vig, O. P.,Sharma, S. D.,Soni, B. R.,Sharma, M. L.
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p. 353 - 355
(2007/10/02)
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