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1.
Chemistry ; 28(1): e202103700, 2022 Jan 03.
Article de Anglais | MEDLINE | ID: mdl-34766655

RÉSUMÉ

A selective ortho,ortho'-functionalization of readily available aryl oxazolines by two successive magnesiations with sBu2 Mg in toluene followed by trapping reactions with electrophiles, such as (hetero)aryl iodides or bromides, iodine, tosyl cyanide, ethyl cyanoformate or allylic bromides (39 examples, 62-99 % yield) is reported. Treatment of these aryl oxazolines with excess oxalyl chloride and catalytic amounts of DMF (50 °C, 4 h) provided the corresponding nitriles (36 examples, 73-99 % yield). Conversions of these nitriles to valuable heterocycles are reported, and a tentative mechanism is proposed.

2.
Org Lett ; 3(18): 2871-3, 2001 Sep 06.
Article de Anglais | MEDLINE | ID: mdl-11529778

RÉSUMÉ

[reaction: see text]. Functionalized arylmagnesium halides, prepared via an iodine-magnesium exchange, undergo a smooth cross-coupling reaction with functionalized primary alkyl iodides and benzylic bromides in the presence of CuCN.2LiCl, either in stoichiometric (with trimethyl phosphite as an additive) or catalytic quantities.

3.
Org Lett ; 3(15): 2395-8, 2001 Jul 26.
Article de Anglais | MEDLINE | ID: mdl-11463325

RÉSUMÉ

[reaction: see text] The hydroboration of tetrasubstituted alkenes and, in particular, bicyclic alkenes with BH(3).THF at 50 degrees C provides, via a highly stereoselective 1,2-rearrangement and a remote C-H activation, a diol in which the relative stereochemistry of three centers has been controlled. A mechanistic study provides general rules for remote C-H activation and leads to new synthetic applications.

4.
Org Lett ; 3(1): 127-30, 2001 Jan 11.
Article de Anglais | MEDLINE | ID: mdl-11429854

RÉSUMÉ

[figure: see text] Various trisubstituted olefins were converted to configurationally stable diorganozinc compounds with high diastereoselectivity. Their reaction with various electrophiles centered on tin, sulfur, bromine, and phosphorus provided the desired substitution products with retention of configuration. Novel, functionalized organocopper reagents such as 4 and chiral diphosphine 5 have been prepared.

5.
Angew Chem Int Ed Engl ; 40(16): 3022-5, 2001.
Article de Anglais | MEDLINE | ID: mdl-12203636

RÉSUMÉ

By a sequence comprising asymmetric hydroboration, boron-zinc exchange, and transmetalation with copper, allylations, alkynylations, and allenylations of unsaturated ketals or acetals can be performed with good enantioselectivities (see scheme, (-)-IpcBH2 =(-)-isopinocampheylborane, TMS=Me3 Si). The products correspond to a formal Michael addition with inversion of polarity.

6.
Chem Commun (Camb) ; (20): 2068-9, 2001 Oct 21.
Article de Anglais | MEDLINE | ID: mdl-12240167

RÉSUMÉ

3-Iodoenoates are converted into the corresponding alkenylmagnesium species with complete retention of configuration of the double bond; both direct reaction and copper(I)-mediated reactions with various electrophiles provide polyfunctional enoates.

9.
Org Lett ; 2(21): 3285-7, 2000 Oct 19.
Article de Anglais | MEDLINE | ID: mdl-11029191

RÉSUMÉ

A catalytic amount of t-BuOK in DMSO allows the addition of ketones or imines to styrenes at 40 degrees C in good to excellent yield. Nitriles add to styrenes in NMP or in DMSO at room temperature.

10.
Chemistry ; 6(15): 2748-61, 2000 Aug 04.
Article de Anglais | MEDLINE | ID: mdl-10985723

RÉSUMÉ

The reaction of cyclic and open-chain diastereomerically pure secondary organoboranes with diisopropylzinc allows the preparation of secondary dialkylzinc reagents with good to excellent retention of configuration as shown by deuterolysis and CuI- and Pd0-mediated reactions with electrophiles. The importance of a high boron-zinc exchange rate to obtain high diastereoselectivity has been shown. Improvement of the configurational stability and stereomeric purity of the zinc intermediates has been obtained by using mono-isopinocampheylborane ((-)-IpcBH2) providing optically active dialkylzinc compounds (up to 96% ee) with enhanced diastereoselectivities.

11.
J Org Chem ; 65(15): 4618-34, 2000 Jul 28.
Article de Anglais | MEDLINE | ID: mdl-10959867

RÉSUMÉ

The reaction of heteroaryl iodides with i-PrMgBr (ca. 1.0 equiv) in THF provides the corresponding magnesiated heterocycles. Functional groups such as an ester, cyano, or chloride functions are tolerated in these new Grignard reagents if the exchange can be performed below -20 degrees C. This is the case for all heterocycles bearing electron-withdrawing groups or chelating functions facilitating the iodine-magnesium exchange. In many cases, the exchange can be extended to heteroaryl bromides, and a case of a chlorine-magnesium exchange is described with tetrachlorothiophene. This new preparation of functionalized heteroarylmagnesium compounds provides after reaction with various electrophiles a new entry to a broad range of polyfunctional pyridines, imidazoles, furanes, thiophenes, pyrroles, antipyrines, and uracil derivatives. The application of the halogen-magnesium exchange in the solid phase allows the performance of solid-phase synthesis, with potential applications for combinatorial chemistry.

12.
Org Lett ; 2(18): 2849-52, 2000 Sep 07.
Article de Anglais | MEDLINE | ID: mdl-10964381

RÉSUMÉ

[reaction: see text] Polysubstituted propadienes are obtained in good to excellent yields by the consecutive carbocupration-homologation-beta-elimination reactions on the easily accessible alkynyl sulfoxides or sulfones. This one-pot reaction also allows the preparation of functionalized allenes.

15.
Chirality ; 12(5-6): 389-95, 2000 Jun.
Article de Anglais | MEDLINE | ID: mdl-10824158

RÉSUMÉ

We have shown that the readily prepared (ferrocenyl)benzylic methyl ethers of type 1 can be ortho-metalated with tert-BuLi with high diastereoselectivity. This reaction has been used to prepare new borane-protected P,N-substituted ferrocenes of type 2 in high diastereomeric and enantiomeric purity. The chiral heterocyclic aminophosphines 2 may be of interest as chelating ligands for asymmetric metal catalysis.

16.
Chemistry ; 6(5): 767-70, 2000 Mar 03.
Article de Anglais | MEDLINE | ID: mdl-10826597

RÉSUMÉ

The iodine-magnesium exchange reaction allows the preparation of polyfunctional aryl, heteroaryl, or alkenyl magnesium reagents at low temperature. These reagents display the typical reactivity of Grignard compounds and undergo various copper-catalyzed reactions such as allylation or 1,4-addition. Using this halogen-metal exchange reaction, it was possible to generate polyfunctional magnesium reagents on the solid phase.

17.
Angew Chem Int Ed Engl ; 38(21): 3212-3215, 1999 Nov 02.
Article de Anglais | MEDLINE | ID: mdl-10556906

RÉSUMÉ

The choice of the substituents at the benzylic position of diphosphane 1 allows the selection of the absolute configuration of the product that is obtained from the transition metal catalyzed enantioselective hydrogenation of various beta-dicarbonyl compounds, alpha-acetamidocinnamic acid derivatives, and dimethyl itaconate (see scheme).

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