- Stereoarrayed CF3-Substituted 1,3-Diols by Dynamic Kinetic Resolution: Ruthenium(II)-Catalyzed Asymmetric Transfer Hydrogenation
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CF3-substituted 1,3-diols were stereoselectively prepared in excellent enantiopurity and high yield from CF3-substituted diketones by using an ansa-ruthenium(II)-catalyzed asymmetric transfer hydrogenation in formic acid/triethylamine. The intermediate mono-reduced alcohol was also obtained in very high enantiopurity by applying milder reaction conditions. In particular, CF3C(O)-substituted benzofused cyclic ketones underwent either a single or a double dynamic kinetic resolution during their reduction. Doubling up: A double dynamic kinetic resolution is described for the ansa-ruthenium(II)-catalyzed asymmetric transfer hydrogenation of diketones in formic acid/triethylamine to yield the title compounds, displaying a stereotriad, in excellent stereopurity. The intermediate mono-reduced alcohols were isolated in very high enantiopurity by using milder reaction conditions.
- Cotman, Andrej Emanuel,Cahard, Dominique,Mohar, Barbara
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supporting information
p. 5294 - 5298
(2016/04/26)
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- Cyclizations of 1,3-bis(trimethylsilyloxy)-1,3-butadienes - A new approach to diverse CF3-substituted fluorenes, dibenzofurans, 9,10-dihydrophenanthrenes and 6H-benzo[c]chromenes
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Trifluoromethyl-substituted fluorenes, dibenzofurans, 9,10- dihydrophenanthrenes and 6H-benzo[c]chromenes were prepared by formal [3+3] cyclizations of 1,3-bis(trimethylsilyloxy)-1,3-butadienes. The reactions proceeded with very good regioselectivity. The
- Büttner, Stefan,Kelzhanova, Nazken K.,Abilov, Zharylkasyn A.,Villinger, Alexander,Langer, Peter
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experimental part
p. 3654 - 3668
(2012/06/18)
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- Exploiting the facile release of trifluoroacetate for the α-methylenation of the sterically hindered carbonyl groups on (+)-sclareolide and (-)-eburnamonine
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An efficient method for the α-methylenation of carbonyl groups is reported, and this transformation is accomplished by a facile elimination of trifluoroacetate during the formation of the olefin. This method represents an improvement beyond existing protocol in cases of steric hindrance, and we have demonstrated the utility of the process across a series of ketones, lactams, and lactones. Additionally, we have applied this method to produce semisynthetic derivatives of the natural products (+)-sclareolide and (-)-eburnamonine, in which the carbonyl group is proximal to bulky functional groups. Mechanistic insight is also provided from a time course of 19F NMR. Biological evaluation of the natural-product-derived enones led to the identification of a derivative of (-)-eburnamonine with significant cytotoxicity (LC50 = 14.12 ?M) in drug-resistant MDA-MB-231 breast cancer cells.
- Riofski, Mark V.,John, Jinu P.,Zheng, Mary M.,Kirshner, Julia,Colby, David A.
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experimental part
p. 3676 - 3683
(2011/06/24)
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