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1.
Org Lett ; 21(12): 4475-4479, 2019 Jun 21.
Artigo em Inglês | MEDLINE | ID: mdl-31184161

RESUMO

The synthesis of 2-aminophosphates is achieved by a SN2-type ring opening reaction of various N-protected or free aziridines with phosphoric acids in a regiospecific and/or enantiospecific way. A one-pot, two-step procedure is also developed enabling direct access to 2-aminophosphates from olefins without isolation of the aziridine intermediates.

2.
J Am Chem Soc ; 2018 Nov 27.
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.

3.
J Org Chem ; 83(20): 12549-12558, 2018 Oct 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.

4.
Org Biomol Chem ; 16(15): 2688-2696, 2018 Apr 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.

5.
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.

6.
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.

7.
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
8.
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.

9.
Chem Commun (Camb) ; 50(2): 177-9, 2014 Jan 07.
Artigo em Inglês | MEDLINE | ID: mdl-24217495

RESUMO

A new chiral silicon-linked tridentate amido-indenyl ligand was developed from indene and enantiopure 1,2-cyclohexanediamine. Its yttrium complex was synthesized, characterized and applied to efficiently catalyze the intramolecular hydroamination of non-activated olefins with up to 97% ee.


Assuntos
Alcenos/química , Complexos de Coordenação/química , Ítrio/química , Aminação , Catálise , Cicloexilaminas/química , Indenos/química , Ligantes , Modelos Moleculares , Estereoisomerismo
10.
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.

11.
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
12.
Angew Chem Int Ed Engl ; 51(31): 7688-91, 2012 Jul 27.
Artigo em Inglês | MEDLINE | ID: mdl-22730219

RESUMO

Three for one: Pyrrolyldipyrromethenes having different functional groups were efficiently synthesized from POCl(3)-promoted condensations between 5-chloro-2-formylpyrrole or isoindole derivatives and suitable pyrrole or indole fragments through a novel nucleophilic aromatic substitution of the initially formed protonated azafulvene rings.


Assuntos
Compostos de Fósforo/química , Pirróis/síntese química , Catálise , Cristalografia por Raios X , Modelos Moleculares , Estrutura Molecular , Pirróis/química
13.
Chem Commun (Camb) ; 48(47): 5880-2, 2012 Jun 14.
Artigo em Inglês | MEDLINE | ID: mdl-22572702

RESUMO

A three-component cascade reaction of salicylaldehyde, malononitrile/cyanoacetate and nitromethane catalysed by chiral tertiary amino-thioureas was developed, which leads to the production of highly functionalized 2-amino-4H-chromenes in good yields with good to excellent enantioselectivities.


Assuntos
Aminas/química , Benzopiranos/síntese química , Tioureia/química , Aldeídos/química , Benzopiranos/química , Metano/análogos & derivados , Metano/química , Nitrilos/química , Nitroparafinas/química , Estereoisomerismo
14.
Chemistry ; 18(9): 2653-9, 2012 Feb 27.
Artigo em Inglês | MEDLINE | ID: mdl-22259029

RESUMO

A series of rare earth metal amido complexes bearing methylene-linked pyrrolyl-amido ligands were prepared through silylamine elimination reactions and displayed high catalytic activities in hydrophosphonylations of aldehydes and unactivated ketones under solvent-free conditions for liquid substrates. Treatment of [(Me(3)Si)(2)N](3)Ln(µ-Cl)Li(THF)(3) with 2-(2,6-Me(2)C(6)H(3)NHCH(2))C(4)H(3)NH (1, 1 equiv) in toluene afforded the corresponding trivalent rare earth metal amides of formula {(µ-η(5):η(1)):η(1)-2-[(2,6-Me(2)C(6)H(3))NCH(2)](C(4)H(3)N)LnN(SiMe(3))(2)}(2) [Ln=Y (2), Nd (3), Sm (4), Dy (5), Yb (6)] in moderate to good yields. All compounds were fully characterized by spectroscopic methods and elemental analyses. The yttrium complex was also characterized by (1)H NMR spectroscopic analyses. The structures of complexes 2, 3, 4, and 6 were determined by single-crystal X-ray analyses. Study of the catalytic activities of the complexes showed that these rare earth metal amido complexes were excellent catalysts for hydrophosphonylations of aldehydes and unactivated ketones. The catalyzed reactions between diethyl phosphite and aldehydes in the presence of the rare earth metal amido complexes (0.1 mol%) afforded the products in high yields (up to 99%) at room temperature in short times of 5 to 10 min. Furthermore, the catalytic addition of diethyl phosphite to unactivated ketones also afforded the products in high yields of up to 99% with employment of low loadings (0.1 to 0.5 mol%) of the rare earth metal amido complexes at room temperature in short times of 20 min. The system works well for a wide range of unactivated aliphatic, aromatic or heteroaromatic ketones, especially for substituted benzophenones, giving the corresponding α-hydroxy diaryl phosphonates in moderate to high yields.


Assuntos
Aldeídos/química , Cetonas/química , Metais Terras Raras/química , Compostos Organometálicos/química , Organofosfonatos/química , Amidas/química , Catálise , Cristalografia por Raios X , Ligantes , Espectroscopia de Ressonância Magnética , Modelos Moleculares , Estereoisomerismo
15.
Dalton Trans ; 40(37): 9447-53, 2011 Oct 07.
Artigo em Inglês | MEDLINE | ID: mdl-21850293

RESUMO

Simple silylamine elimination reactions of calix[4]-pyrrole [R(2)C(C(4)H(2)NH)](4) (R = Me (1), {-(CH(2))(5)-}(0.5) (2)) with 2 equiv. of [(Me(3)Si)(2)N](3)Ln(µ-Cl)Li(THF)(3) (Ln = Nd, Sm, Dy) in reflux toluene, afforded the novel dinuclear alkali metal-free trivalent lanthanide amido complexes (η(5):η(1):η(5):η(1)-R(8)-calix[4]-pyrrolyl){LnN(SiMe(3))(2)}(2) (R = Me, Ln = Nd (3), Sm (4), Dy (5); R = {-(CH(2))(5)-}(0.5), Ln = Nd (6), Sm(7)). The complexes were fully characterized by elemental analyses, spectroscopic analyses and single-crystal X-ray analyses. X-ray diffraction studies showed that each lanthanide metal was supported by bispyrrolyl anions in an η(5) fashion and along with three nitrogen atoms from N(SiMe(3))(2) and two other pyrroyl rings in η(1) modes formed the novel bent-sandwiched lanthanide amido bridged trivalent lanthanide amido complexes, similar to ansa-cyclopentadienyl ligand-supported lanthanide amides with respect to each metal center. The catalytic activities of these organolanthanide complexes as single component l-lactide polymerization catalysts were studied.

16.
J Org Chem ; 76(1): 229-33, 2011 Jan 07.
Artigo em Inglês | MEDLINE | ID: mdl-21142196

RESUMO

The AlCl(3)-catalyzed [3 + 2] cycloaddition reaction of diethyl trans-2,3-disubstituted cyclopropane-1,1-dicarboxylates and aromatic aldehydes was carried out under mild conditions to provide a series of diethyl 2,5-diaryl-4-benzoyltetrahydrofuran-3,3-dicarboxylates in moderate to good yields with excellent diastereoselectivities. While common 2,5-cis products were obtained with electron-neutral or electron-poor aryl aldehydes, the much less common 2,5-trans products were obtained in excellent diastereoselectivities when electron-rich aryl aldehydes were used. The relative configurations of those typical products were confirmed by X-ray crystallographic analyses.


Assuntos
Aldeídos/química , Compostos de Alumínio/química , Cloretos/química , Ciclopropanos/química , Furanos/química , Cloreto de Alumínio , Catálise , Cristalografia por Raios X , Ciclização , Estrutura Molecular , Estereoisomerismo
17.
Dalton Trans ; 39(38): 8994-9, 2010 Oct 14.
Artigo em Inglês | MEDLINE | ID: mdl-20717587

RESUMO

The N-arylaminomethyl substituted pyrrolyl ligand 2-[(2,4,6-Me(3)C(6)H(2))NHCH(2)](C(4)H(3)NH) (1) was synthesized by reduction of 2-[(2,4,6-Me(3)C(6)H(2))N=CH](C(4)H(3)NH) using NaBH(4). Treatment of [(Me(3)Si)(2)N](3)Ln(µ-Cl)Li(THF)(3) with 1 equiv. of 1 in reflux toluene for 24 h, afforded the corresponding trivalent rare earth metal amides with formula {(µ-η(5):η(1)):η(1)-2-[(2,4,6-Me(3)C(6)H(2))NCH(2)]C(4)H(3)N]LnN(SiMe(3))(2)}(2) (Ln = Y(2), Nd(3), Sm(4), Dy(5), Er(6)). All compounds were fully characterised by spectroscopic methods and elemental analyses. The structures of complexes 2, 4 and 6 were determined by single-crystal X-ray analyses. X-Ray analyses discovered that two rare-earth metal ions were bridged by dianion ligand with the pyrrolyl ring which coordinated to one rare earth metal in an η(5) mode, the tethered nitrogen anion and nitrogen atom of the pyrrolyl ring coordinated to another rare earth metal in η(1) modes forming the centrosymmetric dinuclear structures. The rare earth metal complexes as catalysts for the guanylation of aromatic amines were studied. Results showed all rare earth metal complexes exhibited a high catalytic activity on the guanylation of aromatic amines.

18.
Inorg Chem ; 47(12): 5503-11, 2008 Jun 16.
Artigo em Inglês | MEDLINE | ID: mdl-18489086

RESUMO

A series of four coordinate rare earth metal amides with general formula ((CH2SiMe2)[(2,6- IPr2C6H3)N]2)LnN(SiMe3)2(THF) [(Ln = Yb(2), Y (3), Dy (4), Sm (5), Nd (6)] containing a diamido ligand (CH2SiMe2)[(2,6-iPr2C6H3)N]2(2-) with a CH2SiMe2 link were synthesized in good yields via reaction of [(Me3Si)2N]3Ln(III)(mu-Cl)Li(THF)3 with the corresponding diamine (CH2SiMe2)[(2,6-iPr2C6H3)NH]2 (1). All compounds were fully characterized by spectroscopic methods and elemental analyses. The structures of complexes 2, 3, 4, 5, and 6 were determined by single-crystal X-ray analyses. Investigation of the catalytic properties of the complexes indicated that all complexes exhibited a high catalytic activity on the cyclotrimerization of aromatic isocyanates, which represents the first example of cyclopentadienyl-free rare earth metal complexes exhibiting a high catalytic activity and a high selectivity on cyclotrimerization of aromatic isocyanates. The temperatures, solvents, catalyst loading, and the rare earth metal effects on the catalytic activities of the complexes were examined.

19.
J Org Chem ; 72(18): 6763-7, 2007 Aug 31.
Artigo em Inglês | MEDLINE | ID: mdl-17676907

RESUMO

It is demonstrated that the cyclopentadienyl-free simple lanthanide amides [(Me(3)Si)(2)N](3)Ln(mu-Cl)Li(THF)(3)(Ln = La, Sm, Eu, Y, Yb) and Ln[N(SiMe(3))(2)]3 (Ln = Y, Yb) are highly efficient catalysts for the guanylation of both aromatic and secondary amines with a high activity under mild conditions. It is found that these catalysts are compatible with a wide range of solvents and substrates.

20.
J Org Chem ; 71(8): 3149-53, 2006 Apr 14.
Artigo em Inglês | MEDLINE | ID: mdl-16599612

RESUMO

Aromatic aldehydes can be directly converted to the corresponding amides and alcohols in good to excellent yields by the treatment of aromatic aldehydes with lithium amide LiN(SiMe3)2 in the presence of catalytic lanthanide chlorides LnCl3 or by the treatment of aromatic aldehydes with a stoichiometric amount of lanthanide amides [(Me3Si)2N]3Ln(mu-Cl)Li(THF)3 at ambient temperature. The effects of solvents, substitutents on the phenyl ring, and lanthanide metals on the reaction have been examined. The mechanism of the disproportionation reaction was proposed based on the experimental results.


Assuntos
Álcoois/síntese química , Aldeídos/química , Amidas/síntese química , Elementos da Série dos Lantanídeos/química , Álcoois/química , Amidas/química , Catálise , Metais/química , Estrutura Molecular
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