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1.
Chemistry ; 18(19): 5860-3, 2012 May 07.
Artículo en Inglés | MEDLINE | ID: mdl-22461150

RESUMEN

Ironing out the kinks: Efficient new catalytic systems based on iron thiolates are described for the iron-catalyzed cross-coupling of alkyl Grignard reagents with alkenyl halides. The reaction is highly chemo- and stereoselective. With this new procedure, the use of N-methylpyrrolidone as a co-solvent is no longer required.

2.
ACS Org Inorg Au ; 2(4): 359-369, 2022 Aug 03.
Artículo en Inglés | MEDLINE | ID: mdl-35942278

RESUMEN

In the context of cross-coupling chemistry, the competition between the cross-coupling path itself and the oxidative homocoupling of the nucleophile is a classic issue. In that case, the electrophilic partner acts as a sacrificial oxidant. We investigate in this report the factors governing the cross- versus homocoupling distribution using aryl nucleophiles ArMgBr and (hetero)aryl electrophiles Ar'Cl in the presence of an iron catalyst. When electron-deficient electrophiles are used, a key transient heteroleptic [Ar2Ar'FeII]- complex is formed. DFT calculations show that an asynchronous two-electron reductive elimination follows, which governs the selective evolution of the system toward either a cross- or homocoupling product. Proficiency of the cross-coupling reductive elimination strongly depends on both π-accepting and σ-donating effects of the FeII-ligated Ar' ring. The reactivity trends discussed in this article rely on two-electron elementary steps, which are in contrast with the usually described tendencies in iron-mediated oxidative homocouplings which involve single-electron transfers. The results are probed by paramagnetic 1H NMR spectroscopy, experimental kinetics data, and DFT calculations.

3.
Angew Chem Int Ed Engl ; 48(16): 2969-72, 2009.
Artículo en Inglés | MEDLINE | ID: mdl-19288504

RESUMEN

Aryl-alkyl cross-coupling products are obtained by the iron-catalyzed oxidative heterocoupling of organozinc reagents under mild conditions. This novel reaction pathway is versatile, allowing for the use of primary and secondary aliphatic diorganozinc reagents as coupling partners as well as tolerating functionalized aryl- and alkylzinc reagents.

4.
Org Lett ; 21(8): 2679-2683, 2019 04 19.
Artículo en Inglés | MEDLINE | ID: mdl-30964302

RESUMEN

A new robust methodology for gram-scale iron-catalyzed cross-coupling between alkyl Grignard reagents and alkenyl or aryl halides is developed. This method does not require toxic additives such as NMP or expensive ligands. Its efficiency relies on the use of simple alkoxide magnesium salts as additives. On the basis of these results, a new procedure for one-pot synthesis of substituted benzamides from chloroesters is also proposed.

5.
Org Lett ; 10(12): 2389-92, 2008 Jun 19.
Artículo en Inglés | MEDLINE | ID: mdl-18476715

RESUMEN

An efficient new route to prepare stereoselectively terminal conjugated dienes by coupling Grignard reagents and dienol phosphates in the presence of Fe(acac)3 is described. The synthetic utility of this new iron-catalyzed procedure is illustrated by the synthesis of the pheromone of Diparopsis castanea according to a very expeditious strategy.


Asunto(s)
Hierro/química , Feromonas/biosíntesis , Polienos/química , Polienos/síntesis química , Animales , Catálisis , Indicadores y Reactivos , Estructura Molecular , Mariposas Nocturnas/química , Estereoisomerismo
6.
J Org Chem ; 73(17): 6871-2, 2008 Sep 05.
Artículo en Inglés | MEDLINE | ID: mdl-18646858

RESUMEN

The first stereoselective method of preparation of (E)-dienol phosphates from alpha,beta-ethylenic aldehydes is described. The key point is the stereoselective enolization of conjugated alkenals by potassium tert-butoxide in the presence of N-methylpyrrolidinone (NMP).

7.
Org Lett ; 9(17): 3253-4, 2007 Aug 16.
Artículo en Inglés | MEDLINE | ID: mdl-17655319

RESUMEN

The first iron-catalyzed cross-coupling reaction between alkenyl Grignard reagents and n- or s-alkyl bromides is described. The reaction is stereoselective and takes place in the presence of 5 mol % of [Fe(acac)3/TMEDA/HMTA] (1:2:1) under very mild conditions (THF, 0 degrees C, 45 min).

8.
Chem Rev ; 110(3): 1435-62, 2010 Mar 10.
Artículo en Inglés | MEDLINE | ID: mdl-20148539
9.
Chem Rev ; 109(3): 1434-76, 2009 Mar 11.
Artículo en Inglés | MEDLINE | ID: mdl-19209933
10.
Org Lett ; 7(10): 1943-6, 2005 May 12.
Artículo en Inglés | MEDLINE | ID: mdl-15876025

RESUMEN

Iron-catalyzed homo-coupling of simple and functionalized arylmagnesium reagents is described. The reaction is highly chemoselective (CN, COOEt and NO(2) groups are tolerated). The procedure was used to perform intramolecular couplings. This cyclization reaction is the key step of the total synthesis of the N-methylcrinasiadine.


Asunto(s)
Compuestos Heterocíclicos de 4 o más Anillos/síntesis química , Hierro/química , Magnesio/química , Catálisis , Ciclización , Compuestos Heterocíclicos de 4 o más Anillos/análisis , Compuestos Heterocíclicos de 4 o más Anillos/química , Indicadores y Reactivos , Liliaceae/química , Estructura Molecular
12.
Org Lett ; 6(24): 4395-8, 2004 Nov 25.
Artículo en Inglés | MEDLINE | ID: mdl-15548034

RESUMEN

Alkyl- and arylmanganese reagents react with o-chloro or o-bromoaryl ketones to give the substituted ketones in high yields. The cross-coupling reaction is performed under mild conditions (-60 to +40 degrees C, 30 min to 4 h) and takes place with excellent chemoselectivity. [reaction: see text]

14.
Angew Chem Int Ed Engl ; 37(12): 1701-1703, 1998 Jul 03.
Artículo en Inglés | MEDLINE | ID: mdl-29711506

RESUMEN

At -40°C aryl iodides that contain other functional groups can be selectively converted into Grignard reagents, which react with electrophiles such as benzaldehyde in the usual manner [Eq. (a)]. Aryl bromides and iodides that are immobilized as esters on a Wang resin behave analogously.

15.
Chem Commun (Camb) ; 50(64): 8982-4, 2014 Aug 18.
Artículo en Inglés | MEDLINE | ID: mdl-24980393

RESUMEN

The first Cu/Pd-catalyzed decarboxylative cross-coupling of 3,3-diarylacrylic acids with aryl bromides is described. Triarylethylenes were obtained in high yields with excellent stereoselectivities. This methodology was successfully applied to the stereoselective synthesis of (Z)-tamoxifen.


Asunto(s)
Cobre/química , Etilenos/síntesis química , Paladio/química , Tamoxifeno/síntesis química , Acrilatos/química , Bromuros/química , Catálisis , Estereoisomerismo
18.
Org Lett ; 11(2): 277-80, 2009 Jan 15.
Artículo en Inglés | MEDLINE | ID: mdl-19093805

RESUMEN

The cobalt-catalyzed alkylation of aromatic Grignard reagents is performed in good yields by using a new simple and efficient catalytic system: CoCl(2)/TMEDA (1:1). Primary and secondary cyclic or acyclic alkyl bromides were used successfully. The reaction is highly chemoselective since ester, amide, and keto groups are tolerated. The procedure is inexpensive and very easy to carry out on a larger scale.

19.
Org Lett ; 10(22): 5255-6, 2008 Nov 20.
Artículo en Inglés | MEDLINE | ID: mdl-18922008

RESUMEN

Aryl Grignard reagents react stereospecifically with alkenyl halides in the presence of manganese chloride (10%) to afford good yields of cross-coupling products.

20.
J Org Chem ; 69(24): 8525-8, 2004 Nov 26.
Artículo en Inglés | MEDLINE | ID: mdl-15549836

RESUMEN

A straightforward procedure for the regio- and stereoselective synthesis of alpha-hydrazino ketones is described. Manganese enolates and manganese enamines derived from ketones and from the corresponding N-sulfinylimines react with azodicarboxylate esters (DTBAD and DEAD) in a regioselective fashion to afford in good to excellent yields the kinetic alpha-hydrazino ketones as sole or highly prevalent products. When enantiopure N-sulfinyl manganese enamines were used the stereoselectivity of these reactions ranged from 40% to 68% ee.

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