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1.
Inorg Chem ; 58(23): 15983-15992, 2019 Dec 02.
Artículo en Inglés | MEDLINE | ID: mdl-31713428

RESUMEN

A combined synthetic-theoretical study has been undertaken to determine the factors that influence transannulation in azaphosphatranes. The commonly used proazaphosphatrane P(i-BuNCH2CH2)3N and several of its oxidized congeners are used as model systems. The haloazaphosphatranes of P(i-BuNCH2CH2)3N were synthesized, including a rare fluoroazaphopshatrane, and used as references for computational investigations. Comparisons of the experimental and theoretical observations highlight the flexibility observed in transannulated atranes and the potential for multiple local energetic minima depending on the identity of the equatorial substituents for a given azaphosphatrane. Theoretical calculations also identify the role of the ethylene linker in azaphosphatrane bonding, the influence of transannulation on P-electrophile interactions, and the contribution of electrostatic interactions to transannulation.

2.
Angew Chem Int Ed Engl ; 55(20): 6079-83, 2016 05 10.
Artículo en Inglés | MEDLINE | ID: mdl-27094932

RESUMEN

The gold-catalyzed enantioselective hydroazidation and hydroamination reactions of allenes are presented herein. ADC gold(I) catalysts derived from BINAM were critical for achieving high levels of enantioselectivity in both transformations. The sense of enantioinduction is reversed for the two different nucleophiles, allowing access to both enantiomers of the corresponding allylic amines using the same catalyst enantiomer.


Asunto(s)
Alcadienos/química , Complejos de Coordinación/química , Oro/química , Aminas/química , Catálisis , Metano/análogos & derivados , Metano/química , Estereoisomerismo
3.
Angew Chem Int Ed Engl ; 53(17): 4404-7, 2014 Apr 22.
Artículo en Inglés | MEDLINE | ID: mdl-24652820

RESUMEN

The development of a gold(I)-catalyzed sulfination of aryl boronic acids is described. This transformation proceeds through an unprecedented mechanism which exploits the reactivity of gold(I)-heteroatom bonds to form sulfinate anions. Further in situ elaboration of the sulfinate intermediates leads to the corresponding sulfones and sulfonamides, two pharmacophores routinely encountered in drug discovery.


Asunto(s)
Ácidos Borónicos/química , Oro/química , Compuestos Organometálicos/química , Sulfonamidas/síntesis química , Sulfonas/síntesis química , Catálisis , Estructura Molecular , Difracción de Rayos X
4.
Organometallics ; 43(1): 14-20, 2024 Jan 08.
Artículo en Inglés | MEDLINE | ID: mdl-38213984

RESUMEN

Understanding the net donor and electronic properties of pyrrole-based phosphines is critical for guiding their use as ligands. In this study, we compare two isomeric 1- and 2-(diphenylphosphino)methylpyrroles (L1 and L2, respectively) to determine the degree to which N-(phosphino)pyrroles are distinct from aryl- and 2-pyrrolyl phosphines. Ruthenium, rhodium, platinum, and gold complexes as well as selenide derivatives of these ligands are examined using NMR and IR spectroscopy, X-ray crystallography, and cyclic voltammetry. Ligand L2 exhibits net donor properties similar to those of the o-tolyl analogue L3, while L1 shows attenuated electron donation ability. Additionally, a model nickel-catalyzed Kumada coupling reaction using these three ligands was investigated.

5.
Dalton Trans ; 51(20): 7797-7803, 2022 May 24.
Artículo en Inglés | MEDLINE | ID: mdl-35543443

RESUMEN

The synthesis and coordination chemistry of a new class of silyl pincer ligand featuring pyrrole-based linkers is reported. The steric and electronic properties of these bis(phosphinopyrrole)methylsilane ligands were interrogated using their palladium, rhodium, and platinum complexes. The pyrrole-based linker attenuates the donor ability of the ligand relative to its reported 1,2-phenylene congener while maintaining a similar steric profile. Additionally, the silyl donor connected to the N-pyrrolyl groups exhibits a weaker trans influence than the analogous ligand featuring 1,2-phenylene linkers.

6.
J Am Chem Soc ; 133(31): 11964-6, 2011 Aug 10.
Artículo en Inglés | MEDLINE | ID: mdl-21736357

RESUMEN

The design of a supramolecular catalyst capable of high-turnover catalysis is reported. A ruthenium(II) catalyst is incorporated into a water-soluble supramolecular assembly, imparting the ability to catalyze allyl alcohol isomerization. The catalyst is protected from decomposition by sequestration inside the host but retains its catalytic activity with scope governed by confinement within the host. This host-guest complex is a uniquely active supramolecular catalyst, capable of >1000 turnovers.

7.
J Org Chem ; 75(15): 5351-4, 2010 Aug 06.
Artículo en Inglés | MEDLINE | ID: mdl-20590083

RESUMEN

In the presence of TMSOTf and a trialkylamine base, acetic acid undergoes aldol addition to non-enolizable aldehydes under exceptionally mild conditions. Acidic workup yields the beta-hydroxy carboxylic acid. The reaction appears to proceed via a three-step, one-pot process, including in situ trimethylsilyl ester formation, bis-silyl ketene acetal formation, and TMSOTf-catalyzed Mukaiyama aldol addition. Independently synthesized TMSOAc also undergoes aldol additions under similar conditions.

8.
Dalton Trans ; 49(29): 9957-9960, 2020 Aug 07.
Artículo en Inglés | MEDLINE | ID: mdl-32686815

RESUMEN

We report the facile and modular synthesis of unsymmetrical 1,2-bis(phosphino)pyrrole ligands and their coordination chemistry. These ligands offer a promising alternative to their 1,2-bis(phosphino)benzene congeners, retaining a similar steric profile with attenuated electron donation. Proof-of-principle application of a bis(phosphino)pyrrole ligand in a nickel-catalyzed C-N cross-coupling reaction under mild conditions is demonstrated.

9.
Chem Sci ; 7(7): 4091-4100, 2016 Jul 01.
Artículo en Inglés | MEDLINE | ID: mdl-28044096

RESUMEN

Photoinduced, copper-catalyzed cross-coupling can offer a complementary approach to thermal (non-photoinduced) methods for generating C-X (X = C, N, O, S, etc.) bonds. In this report, we describe the first detailed mechanistic investigation of one of the processes that we have developed, specifically, the (stoichiometric) coupling of a copper-thiolate with an aryl iodide. In particular, we focus on the chemistry of a discrete [CuI(SAr)2]- complex (Ar = 2,6-dimethylphenyl), applying a range of techniques, including ESI-MS, cyclic voltammetry, transient luminescence spectroscopy, optical spectroscopy, DFT calculations, Stern-Volmer analysis, EPR spectroscopy, actinometry, and reactivity studies. The available data are consistent with the viability of a pathway in which photoexcited [CuI(SAr)2]-* serves as an electron donor to an aryl iodide to afford an aryl radical, which then reacts in cage with the newly generated copper(II)-thiolate to furnish the cross-coupling product in a non-chain process.

10.
Organometallics ; 33(16): 4169-4172, 2014 Aug 25.
Artículo en Inglés | MEDLINE | ID: mdl-25180022

RESUMEN

A series of gold(III) complexes supported by pyridine-based bis(amidate), bis(carboxylate), and bis(iminothiolate) substituents is reported. These compounds represent rare examples of pincer-ligated gold(III) centers with multiple anionic heteroaom donors. Reactivity and electrochemical studies demonstrate the stability of these compounds and the marked difference in reduction potentials with varying ligand scaffolds.

11.
J Org Chem ; 73(8): 3299-302, 2008 Apr 18.
Artículo en Inglés | MEDLINE | ID: mdl-18335962

RESUMEN

Various ketones, esters, amides, and thioesters add in high yield to dimethyl acetals in the presence of silyl trifluoromethanesulfonates and an amine base. Acetals derived from aryl, unsaturated, and aliphatic aldehydes are all effective substrates. The reaction proceeds in a single reaction flask, with no purification of the intermediate enol silane necessary.


Asunto(s)
Acetales/química , Aldehídos/química , Mesilatos/química , Silanos/síntesis química , Compuestos de Trimetilsililo/química , Acetofenonas/química , Benzaldehídos/química , Espectroscopía de Resonancia Magnética , Estructura Molecular , Silanos/química
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