Asymmetric addition of α-branched cyclic ketones to allenamides catalyzed by a chiral phosphoric acid
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چکیده
منابع مشابه
Direct asymmetric amination of α-branched cyclic ketones catalyzed by a chiral phosphoric acid.
Here we report the direct asymmetric amination of α-substituted cyclic ketones catalyzed by a chiral phosphoric acid, yielding products with a N-containing quaternary stereocenter in high yields and excellent enantioselectivities. Kinetic resolution of the starting ketone was also found to occur on some of the substrates under milder conditions, providing enantioenriched α-branched ketones, ano...
متن کاملAsymmetric addition of α-branched cyclic ketones to allenamides catalyzed by a chiral phosphoric acid† †Electronic supplementary information (ESI) available. See DOI: 10.1039/c5sc04202j Click here for additional data file.
We describe the asymmetric addition of unactivated α-branched cyclic ketones to allenamides catalyzed by a chiral phosphoric acid, generating an all-carbon quaternary stereocenter with broad substrate scope and high enantioselectivity. The products are easily transformed into their corresponding 1,5- and 1,4-ketoaldehyde derivatives, which are both important building blocks in organic synthesis.
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Enantioenriched secondary alcohols represent an important class of molecules found in numerous intermediates, chiral building blocks, and biologically active compounds. Asymmetric reduction of prochiral ketones constitutes the most straightforward way to form these important moieties. Traditionally, stoichiometric amounts of chiral ligands were used together with an aluminium or a boron hydride...
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A novel pyrrolidine-based chiral phosphoproline is an effective bifunctional organocatalyst for the asymmetric Michael addition of ketones to nitroolefins giving high levels of diastereo- and enantio-selectivities (up to > 99 : 1 dr and 96% ee). anti-SR Transition state has the lowest barrier which controls the stereoselectivity, in agreement with experimental results.
متن کاملCatalytic asymmetric addition of diphenylzinc to cyclic , -unsaturated ketones
We have examined the use of our bis(sulfonamide) diol ligand (1) in the asymmetric addition of phenyl groups to cyclic , -unsaturated ketones. Good to excellent enantioselectivities have been obtained with cyclic enones bearing alkyl substituents in the 2 position (71–97% enantiomeric excess). Furthermore, excellent enantioselectivities have been observed in the asymmetric phenylation of cyclic...
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ژورنال
عنوان ژورنال: Chemical Science
سال: 2016
ISSN: 2041-6520,2041-6539
DOI: 10.1039/c5sc04202j