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1.
Org Biomol Chem ; 21(3): 465-478, 2023 01 18.
Artigo em Inglês | MEDLINE | ID: mdl-36508282

RESUMO

As a type of readily available small strained-ring heterocycle, meso-aziridines may undergo catalytic desymmetrizing transformations to empower the rapid construction of diverse nitrogen-containing structures bearing contiguous stereocenters, which have great relevance in natural product synthesis, drug development and the design and synthesis of chiral catalysts/ligands for asymmetric catalysis. This review outlines the advances achieved in the catalytic asymmetric desymmetrization of meso aziridines and highlights some promising avenues for further work in this realm.


Assuntos
Aziridinas , Estereoisomerismo , Aziridinas/química , Catálise , Ligantes
2.
J Org Chem ; 87(1): 453-463, 2022 01 07.
Artigo em Inglês | MEDLINE | ID: mdl-34933553

RESUMO

A tandem insertion of aliphatic nitriles and unactivated alkenes to the N-H bond of secondary aliphatic amines catalyzed by simple trialkyl rare-earth metal complexes was disclosed. This reaction provides a highly atom-economic and stereoselective way to a range of cyclic amidines under mild reaction conditions.


Assuntos
Aminas , Elementos da Série dos Lantanídeos , Alcenos , Amidinas , Catálise
3.
J Org Chem ; 85(2): 430-440, 2020 01 17.
Artigo em Inglês | MEDLINE | ID: mdl-31804077

RESUMO

The Lewis acid-catalyzed annulations between anthranils and γ-butyrolactone-fused donor-acceptor cyclopropanes have been developed. Depending on the anthranils used, such annulations proceeded in a chemodivergent way to produce either bridged cyclic products via [4 + 3] annulation or γ-butyrolactone-fused tetrahydroquinoline products via a cascade process in moderate to high yields. A probable mechanism for the two reaction pathways has been proposed. The reaction could be performed on a gram-scale, and the products could be elaborated to other useful cyclic structures bearing multiple contiguous stereogenic centers.

4.
J Am Chem Soc ; 140(49): 17211-17217, 2018 12 12.
Artigo em Inglês | MEDLINE | ID: mdl-30421916

RESUMO

The first Lewis acid catalyzed stereoconvergent transformation of racemic 2-(hetero)aryl- N-sulfonylaziridines via C-N bond cleavage with nucleophiles is presented. This includes the [3 + 2] annulations with (hetero)aromatic aldehydes and 1,3-disubstituted indoles, asymmetric Friedel-Crafts type reaction with electron-rich (hetero)arenes, and asymmetric aminolysis with amines, providing facile access to chiral 1,3-isoxazolidines, pyrroloindolines, 2-(hetero)arylphenethylamines, and vicinal diamines. This method features a simple and cheaply available complex of Cu(I)-chiral BINAP catalyst, excellent yield and high diastereo- and enantioselectivities, and mild reaction conditions. A mechanism involving type I dynamic kinetic asymmetric transformations (DyKATs) of the racemic aziridines is proposed based on the results of control experiments.

5.
J Org Chem ; 83(20): 12549-12558, 2018 10 19.
Artigo em Inglês | MEDLINE | ID: mdl-30221521

RESUMO

A new Michael addition/intramolecular alkylation sequence of ( Z)-3-(2-bromo-3-arylacryloyl)oxazolidin-2-ones and malonates was developed. By a simple switch of the reaction conditions including the base promoter, solvent, and reaction temperature, both of the cis- and trans-isomers of a series of oxazolidinone-containing 2,3-disubstituted cyclopropane-1,1-diesters could be obtained in good-to-excellent yields and with an excellent diastereoselectivity. The utility of the cyclopropane products was demonstrated in the diastereoselective syntheses of (±)-urinaligran and a stereoisomer of (±)-virgatusin involving the AlCl3-promoted [3+2] annulation with veraldehyde or piperonal as the key step.

6.
J Org Chem ; 83(1): 174-184, 2018 01 05.
Artigo em Inglês | MEDLINE | ID: mdl-29219307

RESUMO

The [3 + 2] annulations of γ-butyrolactone fused donor-acceptor (D-A) cyclopropanes with aromatic isothiocyanates and dialkyl carbodiimides promoted by FeCl3 is reported. A series of bicyclic/polycyclic γ-butyrolactone fused thioimidates and γ-butyrolactone fused amidines containing four contiguous stereogenic centers were obtained in excellent yields as single stereoisomers.

7.
Org Biomol Chem ; 16(15): 2688-2696, 2018 04 18.
Artigo em Inglês | MEDLINE | ID: mdl-29582023

RESUMO

An enantiospecific [3 + 2] annulation of γ-butyrolactone fused cyclopropanes with aromatic aldehydes was realized under Lewis acid catalysis. This method provides facile access to a series of chiral furanolignan derivatives bearing multiple contiguous stereogenic centers in good-to-excellent yields, exclusive diastereoselectivities and excellent enantiopurities under mild reaction conditions. Elaboration work on the product of this reaction delivers stereoisomeric analogues of (+)-virgatusin and suggests a structural revision might be necessary for a previously reported isolated natural product.

8.
Angew Chem Int Ed Engl ; 56(2): 650-654, 2017 01 09.
Artigo em Inglês | MEDLINE | ID: mdl-27918132

RESUMO

The kinetic resolution of 2-aryl-N-tosylaziridines and the asymmetric desymmetrization of meso-N-tosylaziridines by ring openings with various primary and secondary anilines, and aliphatic amines as nucleophile have been realized by using a single silver(I)/chiral diphosphine complex as catalyst for the first time. The simple starting materials, broad scope, and easy scalability render this protocol a practical way to chiral vicinal diamine derivatives.

9.
Org Biomol Chem ; 14(3): 1024-30, 2016 Jan 21.
Artigo em Inglês | MEDLINE | ID: mdl-26633006

RESUMO

An organocatalytic dearomative [3 + 2]-annulation of N-alkyl-3-alkylindoles with quinone monoketals is developed. The reaction provides a mild and straightforward way to various benzofuro[2,3-b]indolines of potential biological and pharmaceutical interest in moderate to good yields. Moreover, when 3-phenylindole, a problematic substrate in previous relevant studies, was used as the substrate under the otherwise same reaction conditions, a novel 1,2-shift of the phenyl group occurred followed by aromatization to provide 2,3-diaryl indoles useful for cancer therapy studies in moderate yields.


Assuntos
Ácidos/química , Benzoquinonas/química , Indóis/química , Indóis/síntese química , Catálise , Ciclização , Modelos Moleculares , Estrutura Molecular
10.
Beilstein J Org Chem ; 12: 725-31, 2016.
Artigo em Inglês | MEDLINE | ID: mdl-27340464

RESUMO

A highly enantioselective α-amination of 3-substituted oxindoles with azodicarboxylates catalyzed by amino acids-derived chiral phosphine catalysts is reported. The corresponding products containing a tetrasubstituted carbon center attached to a nitrogen atom at the C-3 position of the oxindole were obtained in high yields and with up to 98% ee.

11.
J Am Chem Soc ; 137(32): 10088-91, 2015 Aug 19.
Artigo em Inglês | MEDLINE | ID: mdl-26204063

RESUMO

The first Lewis acid catalyzed [3 + 2] annulation of indoles and 2-aryl-N-tosylaziridines was realized by using copper(I)/chiral diphosphine complexes as a catalyst. With this method, a variety of uniquely substituted chiral pyrroloindolines bearing multiple contiguous stereogenic centers were facilely accessed in a straightforward, high-yielding, and highly stereoselective way under mild conditions.

12.
Angew Chem Int Ed Engl ; 54(6): 1775-9, 2015 Feb 02.
Artigo em Inglês | MEDLINE | ID: mdl-25515428

RESUMO

The combination of a new bifunctional phosphine and an acrylate generate a zwitterion in situ and it serves as an efficient catalyst for asymmetric reactions through a homogeneous ion-pairing mode. This new catalytic system has been successfully applied to Mannich-type reactions to give excellent results and it demonstrates a broad substrate scope. Such reactivity is not accessible with general organophosphine catalytic modes. Preliminary investigations into the mechanism are also presented.

13.
Org Biomol Chem ; 12(8): 1351-6, 2014 Feb 28.
Artigo em Inglês | MEDLINE | ID: mdl-24435592

RESUMO

Polysubstituted pyrroles were regioselectively synthesized in moderate to good yields via the copper acetate-catalyzed [3 + 2] annulation reaction of readily accessible aziridines and nitroalkenes. This reaction was proposed to proceed through a key azomethine ylide intermediate generated by selective C-C bond cleavage of the aziridine followed by annulation with nitroalkenes under aerobic conditions.


Assuntos
Alcenos/química , Aziridinas/química , Nitrocompostos/química , Pirróis/síntese química , Catálise , Cobre/química , Pirróis/química , Estereoisomerismo
14.
J Org Chem ; 78(19): 9781-90, 2013 Oct 04.
Artigo em Inglês | MEDLINE | ID: mdl-24010962

RESUMO

A chemoselective phosphine-catalyzed cycloaddition or dienylation reaction between trifluoromethyl-substituted ketones and bis-substituted allenoates was described. Under the catalysis of triarylphosphine, the reaction gave a range of trifluoromethylated tetrahydrofurans with broad substrate tolerance and good to excellent stereoselectivity, while the use of trialkylphosphine switched the reaction pathway to furnish CF3-substituted dienyl tertiary alcohols chemoselectively. Moreover, a preliminary study on the asymmetric version of the reaction was also performed, which represents the first example of a phosphine-catalyzed asymmetric reaction between allenoates and carbonyl compounds.


Assuntos
Furanos/química , Hidrocarbonetos Fluorados/química , Cetonas/química , Fosfinas/química , Catálise , Reação de Cicloadição , Estrutura Molecular , Estereoisomerismo
15.
J Org Chem ; 78(11): 5393-400, 2013 Jun 07.
Artigo em Inglês | MEDLINE | ID: mdl-23634966

RESUMO

A series of cis-2,3-disubstituted cyclopropane 1,1-diesters were examined in the AlCl3-promoted [3 + 2]-annulations with aldehydes. In this reaction, these cis-cyclopropanes displayed reactivities starkly different from their trans counterparts in terms of the high chemical yields (up to 98%) and provided the desired annulation products with excellent diastereomeric purity. This protocol provides a facile and highly stereoselective way to construct synthetically useful pentasubstituted tetrahydrofurans not easily accessible using other methods.


Assuntos
Aldeídos/química , Ciclopropanos/química , Furanos/síntese química , Ésteres , Furanos/química , Estrutura Molecular , Estereoisomerismo
16.
Org Biomol Chem ; 11(45): 7859-68, 2013 Dec 07.
Artigo em Inglês | MEDLINE | ID: mdl-24129618

RESUMO

cis-2,3-Disubstituted cyclopropane 1,1-diesters were found to be much more reactive than their corresponding trans-isomers in the AlCl3-promoted [3 + 2]-annulations with isothiocyanates. The reaction with the cis-cyclopropanes proceeded to completion within minutes, providing a variety of densely substituted diastereomerically pure 2-iminodihydrothiophenes in moderate to excellent yields.

17.
Org Lett ; 25(15): 2577-2581, 2023 Apr 21.
Artigo em Inglês | MEDLINE | ID: mdl-37052381

RESUMO

Under the catalysis of simple Lewis acid catalysts, 2-(1-aroylcyclopropyl)malonates demonstrated unique reactivities in annulation reactions with aryl/alkyl aldehydes, paraformaldehyde, and 1,3,5-triazinanes. Three types of structurally diverse cyclic products that are otherwise not easy to obtain were generated in moderate to good yields and excellent diastereoselectivities. Possible reaction pathways leading to these products were proposed on the basis of the results of control experiments.

18.
J Am Chem Soc ; 134(8): 3615-8, 2012 Feb 29.
Artigo em Inglês | MEDLINE | ID: mdl-22313246

RESUMO

A Pd(II)/Brønsted acid catalyzed migratory ring expansion for the synthesis of indene derivatives possessing a stereogenic spirocyclic carbon center was developed. This transformation is believed to mechanistically proceed via enantioselective allylic C-H activation with concomitant semipinacol ring expansion to the nascent π-allylpalladium species. Enantioselectivities as high as 98% ee were attainable.


Assuntos
Ácidos/química , Compostos Alílicos/química , Compostos Organometálicos/química , Paládio/química , Compostos de Espiro/síntese química , Catálise , Estrutura Molecular , Compostos de Espiro/química , Estereoisomerismo
19.
Org Biomol Chem ; 10(16): 3195-201, 2012 Apr 28.
Artigo em Inglês | MEDLINE | ID: mdl-22419060

RESUMO

An asymmetric organocatalytic [4 + 2] cycloaddition between α-substituted allenoates and dual activated olefins using bifunctional N-acyl aminophosphine catalysts is described. The use of 2-cyano acrylate derived olefins led to the first successful incorporation of an electrophile derived from an aliphatic aldehyde into this reaction.

20.
Org Lett ; 24(49): 8948-8953, 2022 Dec 16.
Artigo em Inglês | MEDLINE | ID: mdl-36449566

RESUMO

Herein, we synthesized and characterized a binuclear copper(I) complex supported by the indolyl-based ligand. Employing this complex as catalyst, we have developed a three-component intermolecular trifluoromethylazolation of alkenes to deliver various trifluoromethylated azole derivatives. The method features exclusive chemo- and regioselectivity, a broad scope of alkenes and oxazoles, thiazoles, and good tolerance of functional groups under mild conditions. Preliminary mechanistic studies support a radical process for the transformation.

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