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1.
Chem Commun (Camb) ; 58(46): 6653-6656, 2022 Jun 08.
Artigo em Inglês | MEDLINE | ID: mdl-35593224

RESUMO

A Cu-catalyzed asymmetric 1,6-conjugate addition of in situ generated para-quinone methides (p-QMs) with ß-ketoester has been developed to construct a ketoester skeleton bearing an adjacent tertiary-quaternary carbon stereocenter in good yields and high enantioselectivities. This is the first example of metal-catalyzed asymmetric transformations of the in situ generated p-QMs, avoiding using pre-synthesized p-QMs requiring bulky 2,6-substitutions and highlighting a new dual catalytic activation with the chiral bis(oxazoline)-metal complex acting as a normal Lewis acid to activate the ß-ketoesters and a source of Brønsted acid responsible for generating the p-QMs in situ.


Assuntos
Cobre , Indolquinonas , Catálise , Metais
2.
Org Lett ; 23(7): 2471-2476, 2021 Apr 02.
Artigo em Inglês | MEDLINE | ID: mdl-33733793

RESUMO

A sequential enantioselective conjugate addition/hydroalkoxylation between in situ generated ortho-quinomethanes and ynones by combining bifunctional squaramide and DBU catalysis has been developed. A variety of eight-membered cyclic ethers with two contiguous tertiary stereocenters were obtained in high yields with excellent stereoselectivities. This reaction not only provides a new strategy for constructing enantioenriched eight-membered cyclic ethers but also demonstrates the practicability of ynones as C4-syntons for the synthesis of chiral medium-membered rings.

3.
J Org Chem ; 85(15): 9491-9502, 2020 Aug 07.
Artigo em Inglês | MEDLINE | ID: mdl-32692168

RESUMO

The functionalization of indoles in the carbocyclic ring has been achieved via organocatalytic enantioselective Friedel-Crafts benzhydrylation of hydroxyindoles with in situ generated ortho-quinomethanes in oil-water biphases, allowing an efficient access to varied diarylindolylmethanes with a wide substrate scope. The high yields, excellent stereoselectivities, mild conditions, low catalyst loading, and easy scalability also demonstrated the interest of this novel methodology.

4.
Org Biomol Chem ; 18(26): 4927-4931, 2020 07 08.
Artigo em Inglês | MEDLINE | ID: mdl-32573633

RESUMO

A highly enantioselective homogeneous fluorination of cyclic ß-keto esters catalyzed by diphenylamine linked bis(oxazoline)-Cu(OTf)2 complexes has been established in a continuous flow microreactor. The microreactor allowed an efficient transformation with reaction times ranging from 0.5 to 20 min, and the desired products were afforded in high yields (up to 99%) with excellent enantioselectivities (up to 99% ee) at a low catalyst loading of 1 mol%.

5.
Org Biomol Chem ; 18(13): 2398-2404, 2020 04 01.
Artigo em Inglês | MEDLINE | ID: mdl-32191253

RESUMO

A highly regioselective and enantioselective N-alkylation of isoxazol-5-ones with para-quinone methides promoted by bi-functional squaramide catalysts was developed. This unexpected asymmetric N-addition of isoxazolinones afforded a series of enantioenriched N-diarylmethane substituted isoxazolinones with high yields and enantioselectivities (up to 97 : 3 er). This reaction not only provides a useful approach for intermolecular chiral C-N bond formation but also demonstrates the immense potential of isoxazol-5-ones as N-nucleophiles in catalytic asymmetric reactions.

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