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1.
Molecules ; 25(3)2020 Feb 03.
Artigo em Inglês | MEDLINE | ID: mdl-32028657

RESUMO

A highly efficient quinine-derived primary-amine-catalyzed asymmetric aldol addition of hydroxyacetone to arylglyoxals is described. Structurally diverse anti-2,3-dihydroxy-1,4-diones were generated in high yields, with good diastereoselectivities and enantioselectivities.

2.
Org Lett ; 21(24): 10090-10093, 2019 Dec 20.
Artigo em Inglês | MEDLINE | ID: mdl-31820650

RESUMO

The first catalytic asymmetric alkenylation of isatin imines is described. The reaction, which is promoted by a chiral bis(oxazoline)-copper complex, gives structurally diverse 3-alkenyl-3-aminooxindole derivatives in excellent yields, and with excellent diastereoselectivities and high-to-excellent enantioselectivities. The products can be readily converted to polycyclic indole derivatives without loss of enantioselectivity. A plausible chirality-induced mechanism is proposed to explain the observed stereoselective control.

3.
J Am Chem Soc ; 141(13): 5159-5163, 2019 04 03.
Artigo em Inglês | MEDLINE | ID: mdl-30896937

RESUMO

A chiral aldehyde is rationally combined with a Lewis acid and a transition metal for the first time to form a triple catalytic system. This cocatalytic system exhibits good catalytic activation and stereoselective-control abilities in the asymmetric α-allylation reaction of N-unprotected amino acid esters and allyl acetates. Optically active α,α-disubstituted α-amino acids (α-AAs) are generated in good yields (up to 87%) and enantioselectivities (up to 96% ee). Preliminary mechanism investigation indicates that the chiral aldehyde 3f acts both as an organocatalyst to activate the amino acid ester via the formation of a Schiff base, and as a ligand to facilitate the nucleophilic attack process by coordinating with π-allyl Pd(II) species.

4.
Org Lett ; 21(4): 1161-1164, 2019 02 15.
Artigo em Inglês | MEDLINE | ID: mdl-30694686

RESUMO

The first catalytic asymmetric Diels-Alder reaction of 3-vinylindole and nitroolefin is described. In the promotion of organocatalyst 3j, structurally diverse 1-nitro-hydrocarbazoles are produced in moderate-to-good yields and high-to-excellent enantioselectivities. All of these products are obtained as a single diastereoisomer. The 1-nitro-hydrocarbazole compounds can be converted into 1-amino-hydrocarbazole derivatives and structurally complex ring-fused indoles enantioseletively. Possible transition states were investigated by control experiments and DFT calculations.

5.
J Am Chem Soc ; 140(30): 9774-9780, 2018 08 01.
Artigo em Inglês | MEDLINE | ID: mdl-29995401

RESUMO

Chiral aldehyde catalysis is uniquely suitable for the direct asymmetric α-functionalization of N-unprotected amino acids, because aldehydes can reversibly form imines. However, there have been few successful reports of these transformations. In fact, only chiral aldehyde catalyzed aldol reactions of amino acids and alkylation of 2-amino malonates have been reported with good chiral induction. Here, we report a novel type of chiral aldehyde catalyst based on face control of the enolate intermediates. The resulting chiral aldehyde is the first efficient nonpyridoxal-dependent catalyst that can promote the direct asymmetric α-functionalization of N-unprotected glycine esters. Possible transition states and the proton transfer process were investigated by density functional theory calculations.

6.
Org Lett ; 19(5): 1120-1123, 2017 03 03.
Artigo em Inglês | MEDLINE | ID: mdl-28212042

RESUMO

A highly efficient alkenylation reaction of arylglyoxals with 3-vinylindoles catalyzed by chiral calcium phosphate is described. Structurally diverse allylic alcohols bearing indole and carbonyl units are prepared in excellent yields, good diastereoselectivities, and high to excellent enantioselectivities. These products are good building blocks for the synthesis of polysubstituted chiral tetrahydrocarbozol-2-ones. The mechanism study indicates that the most likely role of the catalyst is to activate the hydrate of arylglyoxal and control the stereoselectivity via desymmetric coordination.

7.
Org Lett ; 18(23): 6200-6203, 2016 12 02.
Artigo em Inglês | MEDLINE | ID: mdl-27934374

RESUMO

A simple Brønsted acid catalyzed tandem reaction, including intermolecular nucleophilic addition, substitution and intramolecular cyclization, in a one-pot manner is described. Thirty two 2-indolyl substituted carbazoles are generated in good to excellent yields. Based on this tandem reaction strategy, the poly(1,4-carbazole) is prepared for the first time. Preliminary studies indicate that the poly(1,4-carbazole) has good thermostability and optical properties.

8.
Org Lett ; 18(15): 3874-7, 2016 08 05.
Artigo em Inglês | MEDLINE | ID: mdl-27435050

RESUMO

The 3-vinyl indole is used as a nucleophile to react with aromatic and aliphatic imines. Chiral 3-substituted indoles bearing multiple functional groups are produced with up to 99% yield, a 98:2 E/Z ratio, and 97% ee. A possible mechanism is proposed to explain the observed stereoselectivities. This strategy provides an efficient way for the preparation of novel chiral 3-substituted indoles.

10.
Org Lett ; 17(15): 3922-5, 2015 Aug 07.
Artigo em Inglês | MEDLINE | ID: mdl-26218556

RESUMO

The highly efficient, regioselective, and enantioselective transfer hydrogenation of α-keto ketimines and reductive amination of diketones by Brønsted acid catalysis is described. A series of chiral α-amino ketones is prepared in high yields (up to >99%), excellent regioselectivities (up to >99:1), and enantioselectivities (up to 98% ee). This method has broad substrate scope.

11.
Org Lett ; 16(24): 6472-5, 2014 Dec 19.
Artigo em Inglês | MEDLINE | ID: mdl-25487704

RESUMO

This work describes an efficient α-alkylation reaction of α-amino aldehydes with 3-indolylmethanols. In the promotion of catalyst 3f, the target products were obtained in high yields (up to 99%), good diastereoselectivities (up to 88:12), and excellent enantioselectivities (up to 96% ee). The direct alkylation products can be readily converted into other tryptophan derivatives without the loss of stereoselectivities.

12.
J Org Chem ; 77(7): 3589-94, 2012 Apr 06.
Artigo em Inglês | MEDLINE | ID: mdl-22375896

RESUMO

The diastereoselectively switchable enantioselective Mannich reaction of isatin imines with hydroxyacetone is reported. The chiral primary amino acid catalyzed this Mannich reaction to afford both anti- and syn-Mannich adducts in high yields, good diastereoselectivities, and enantioselectivities. The reason for the solvent control of the diastereoselectivity phenomenon was investigated.


Assuntos
Acetona/análogos & derivados , Iminas/química , Indóis/síntese química , Isatina/química , Solventes/química , Acetona/química , Catálise , Indóis/química , Estrutura Molecular , Oxindois , Estereoisomerismo
15.
Org Lett ; 11(20): 4620-3, 2009 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-19746916

RESUMO

The H8-BINOL-derived, phosphoric acid catalyzed, highly enatioselective alkylation reaction of enamides with indolyl alcohols has been described. A phosphoric acid derived from H8-BINOL enabled an asymmetric alpha-alkylation of enamides with indolyl alcohols to give beta-aryl 3-(3-indolyl)propanones in high yields (up to 96%) and with excellent enantioselectivity (up to 96% ee).

16.
J Am Chem Soc ; 129(45): 13927-38, 2007 Nov 14.
Artigo em Inglês | MEDLINE | ID: mdl-17956093

RESUMO

The chiral bimetallic oxovanadium complexes have been designed for the enantioselective oxidative coupling of 2-naphthols bearing various substituents at C6 and/or C7. The chirality transferring from the amino acid to the axis of the biphenyl in oxovanadium complexes 2 was found to occur with the use of UV and CD spectra and DFT calculation. The homo-coupling reaction with oxygen as the oxidant was promoted by 5 mol % of an oxovanadium complex derived from L-isoleucine and achiral biphenol to afford binaphthols in nearly quantitative yields with high enantioselectivities of up to 98% ee. An oxovanadium complex derived from L-isoleucine and H8-binaphthol is highly efficient at catalyzing the air-oxidized coupling of 2-naphthols with excellent enantioselectivities of up to 97% ee. 51V NMR study shows that the oxovanadium complexes have two vanadium(V) species. Kinetic studies, the cross-coupling reaction, and HRMS spectral studies on the reaction have been carried out and illustrate that two vanadium(V) species are both involved in catalysis and that the coupling reaction undergoes a radical-radical mechanism in an intramolecular manner. Quantum mechanical calculations rationalize the importance of the cooperative effects of the axial chirality matching S-amino acids on the stereocontrol of the oxidative coupling reaction. The application of the transformation in the preparation of chiral ligands and conjugated polymers confirms the importance of the current process in organic synthesis.


Assuntos
Naftóis/química , Naftóis/síntese química , Compostos Organometálicos/química , Oxidantes/química , Oxigênio/química , Vanadatos/química , Ar , Catálise , Técnicas de Química Combinatória , Modelos Químicos , Estrutura Molecular , Compostos Organometálicos/síntese química , Oxirredução , Estereoisomerismo
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