Copper-catalyzed electrophilic amination of diorganozinc reagents

The copper-catalyzed electrophilic amination of diorganozinc reagents employing O-acyl N,N-dialkyl hydroxylamine derivatives as aminating agents is described. This reaction offers a general method for the preparation of tertiary amines in high yields and is noteworthy for its convenience both in terms of reaction conditions employed (room temperature, 相似文献   

Electrophilic amination of diorganozinc reagents by oxaziridines

Electrophilic amination of organozinc reagents by oxaziridines has been studied. Diorganozinc reagents R₂Zn (R = alkyl or aryl) react with N-Boc oxaziridine to afford N-Boc protected primary amines BocNHR in moderate to good yields. No additives are needed in this reaction, which proceeds at 0 °C. We suggest that the presence of two heteroatoms in oxaziridine allows Lewis base activation of the diorganozinc reagent.     

Copper-catalyzed electrophilic amination of functionalized diarylzinc reagents

The copper-catalyzed electrophilic amination of functionalized diarylzinc reagents with O-acyl hydroxylamines allows for the preparation of functionalized tertiary arylamines in high yields, and is noteworthy for the mild reaction conditions employed. The functionalized diarylzinc reagents were prepared via an iodine/magnesium exchange of the corresponding aryl iodide followed by transmetalation of the resultant Grignard species with ZnCl(2).     

Cosolvent‐promoted electrophilic amination of organozinc reagents

In this study, we aimed to develop a simple and efficient method for the electrophilic amination of organozinc reagents. For this reason, 12 cosolvents were screened in the electrophilic amination of ordinary organozinc reagents. By the use of a cosolvent, an easily applicable and high‐yielding method for the preparation of arylamines by electrophilic amination of arylzinc reagents was developed. Copyright © 2009 John Wiley & Sons, Ltd.     

Synthesis of hindered anilines: copper-catalyzed electrophilic amination of aryl boronic esters

No longer a hindrance: copper-catalyzed electrophilic amination of aryl boronic esters is accomplished under mild reaction conditions using 2.5-5.0 mol % of a catalyst derived from copper tert-butoxide and Xantphos ligand. The reaction tolerates a wide range of functional groups and can be used to prepare some of the most hindered anilines made to date.     

Highly efficient catalytic system for electrophilic amination of arylzinc reagents

The effect of catalyst on the yield of amine in the amination of three classes of arylzinc reagents with acetone oxime O‐tosylate was investigated. Since they allowed the preparation of arylamines in excellent yields in the presence of a minimum amount of copper (I) or copper (II) compounds, the catalytic systems using copper (I) or copper (II) combined with a P‐, N‐ or S‐donor ligand were revealed to be the best catalysts for the electrophilic amination of arylzinc reagents with acetone oxime O‐tosylate in the presence of DMPU. Copyright © 2009 John Wiley & Sons, Ltd.     

Catalytic asymmetric synthesis of alpha,alpha,alpha-trifluoromethylamines by the copper-catalyzed nucleophilic addition of diorganozinc reagents to imines

[reaction: see text] A copper-catalyzed asymmetric addition of diorganozinc reagents to N-phosphinoylimines has been developed for the synthesis of chiral alpha,alpha,alpha-trifluoromethylamines. The trifluoromethyl ketimines, generated in situ from the corresponding hemiaminals, led to the chiral amides in high yields (71-89%) and excellent enantiocontrol (91-99% ee).     

Reactivity of mixed organozinc and organocopper reagents. 3. Atom economic electrophilic amination of methyl arylzinc reagents

Reaction of methyl arylzincs with acetone O‐(mesitylenesulfonyl)oxime in THF in the presence of CuCN at room temperature is efficient in selective electrophilic amination of aryl carbanions. This procedure allows for the preparation of arylamines in moderate to good yields and provides an efficient and atom economic alternative to existing amination methods for diarylzincs. Copyright © 2009 John Wiley & Sons, Ltd.     

Preparation of aryl-alkylamines via electrophilic amination of functionalized arylazo tosylates with alkylzinc reagents

[reaction: see text] A new electrophilic amination reaction of functionalized arylazo tosylates with alkylzinc halides or dialkylzinc reagents in THF leads to the corresponding hydrazines. A facile cleavage of the N-N bond is achieved using Raney nickel in refluxing ethanol, leading to substituted secondary aryl-alkylamines in 45-79% yield.     

Aryl C-N bond formation by electrophilic amination of diarylcadmium reagents with O-substituted ketoximes

Diorganocadmium reagents cannot react with ketoxime at room temperature. CuCN catalysis allows diarylcadmium reagents to react with ketoxime and to give corresponding arylamines in good to high yields at room temperature. According to the electronic effects of the substituent attached to the aromatic ring, functionalized diarylcadmium reagents show meta-para selectivity in their amination reactions. Also compared to diarylzinc reagents, diarylcadmium reagents react with O-substituted ketoxime under milder reaction conditions and they form corresponding arylamines in higher yields. CuCN cannot help dialkyl-, dicycloalky-, and dibenzylcadmium reagents to react with ketoxime. Our Aryl C-N bond formation method does not include cadmium excretion into the environment.     

Synthesis of primary amines by the electrophilic amination of Grignard reagents with 1,3-dioxolan-2-one O-sulfonyloxime

Primary amines are prepared by the electrophilic amination of Grignard reagents with 4,4,5,5-tetramethyl-1,3-dioxolan-2-one O-phenylsulfonyloxime and the acidic hydrolysis of the resulting imines. [reaction: see text]     

Mechanistic studies of copper(I)-catalyzed allylic amination

The reactions of nitrosobenzene and N,N'-diethyl-4-nitrosoaniline with [Cu(CH3CN)4]PF6 provide novel Cu(I) complexes, [Cu(PhNO)3]PF6 (1) and [Cu(Et2NPhNO)3]PF6 (2); in 2 the copper atom is N-coordinated to the nitrosoarenes in a distorted trigonal planar geometry. Complex 1 is strongly implicated as a reactive intermediate in the Cu(I)-catalyzed allylic amination of olefins based on (i) its isolation from the catalytic reaction, (ii) its stoichiometric regioselective allylic amination of alpha-methyl styrene (AMS), (iii) the non-involvement of free PhNO in its amination of AMS, and (iv) its function as a catalyst for the amination of alkenes from phenylhydroxylamine. The reaction between AMS and 1 (80 degrees C, dioxane) is first order in both alkene and 1. Relative rate studies of the reaction of 1 with para substituted AMS derivatives gives a Hammett rho value of -0.035. Alkene adducts isolated from the reaction of 1 with styrene and alpha-methylstyrene are formulated as [(PhNO)3Cu(eta(2)-alkene)]PF6 (7,8) on the basis of spectroscopic characterization and thermolysis. PM3 and DFT MO calculations support the role of [(alkene)Cu(RNO)3]+ and (eta(1)- or eta(3)-allyl)Cu(RNO)2(RNHOH)+ complexes as probable catalytic intermediates and address the origin of the distinctive reaction regioselectivity. A mechanistic scheme is proposed which is consistent with the accumulated experimental and computational results.     

Comparison of electrophilic amination reagents for N-amination of 2-oxazolidinones and application to synthesis of chiral hydrazones

Comparison of several hydroxylamine-based electrophilic ammonia equivalents in the N-amination of 2-oxazolidinones revealed that O-(p-nitrobenzoyl)hydroxylamine (NbzONH(2)) and sodium hydride in dioxane is a superior reagent combination for this purpose. Practical preparations of a variety of chiral N-acylhydrazones by this method gave yields ranging from 45 to 95%. Methods for exchange or removal of the aldehyde component have been developed, making this a general route to chiral N-acylhydrazones of interest for asymmetric synthesis applications.     

Asymmetric electrophilic amination of enolates by a chiral N-alkoxycarbonyloxaziridine

A new chiral 3-aryl-N-alkoxycarbonyloxaziridine, derived from menthol, has been prepared and tested as a reagent for asymmetric electrophilic amination of enolates. The aminated products were obtained in low diastereoselectivities of up to 21% d.e.     

Palladium-/copper-catalyzed regioselective amination and chloroamination of indoles

A palladium-/copper-catalyzed intermolecular C-H amination reaction of indoles has been developed. This reaction proceeds in good to excellent yields to produce a variety of 2-amino-substituted indoles and exhibits excellent regioselectivity at room temperature. Furthermore, chloroamination of indoles provides a simple method for the construction of C-N and C-Cl bonds in one step.     

Mechanistic studies on the nucleophilic reaction of porphyrins with organolithium reagents.

Porphyrins react readily with organolithium reagents under substitution of free meso positions. As this method has proven to be very versatile for the preparation of a wide range of meso substituted porphyrins, a mechanistic study of the reaction was undertaken using 5,15-diaryl- and dialkyl substituted porphyrins, 2,3,7,8,12,13,17,18-octaethylporphyrin, and the respective nickel(II) complexes. A combination of deuteration experiments, electronic absorption spectroscopy of the reactive intermediates, trapping of intermediates with organic electrophiles, and reaction at different pH values showed significant differences in the reaction pathways of free base porphyrins and metalloporphyrins. In both cases the reaction proceeds initially under formation of phlorin like intermediates which are stable in water. For the Ni(II)phlorins a mesomeric carbanionic form with a highly distorted structure exists that can react as a nucleophile with electrophiles such as RI, H+, or D+. In the latter case a protonation-deprotonation equilibrium involving porphodimethen intermediates has to be assumed. Free base phlorins do not react as nucleophiles but can undergo H/D exchange reactions in strongly acidic media.     

General method for the expedient synthesis of salt-free diorganozinc reagents using zinc methoxide

The effect of counterions has a great impact on the solubility of magnesium salts in Et2O. By reacting Zn(OMe)2 with readily available Grignard reagents, it was possible to induce the complete precipitation of magnesium salts and then obtain salt-free diorganozinc reagents after centrifugation/filtration. This practical method to generate dialkylzinc reagents as well as mixed diorganozinc reagents was successfully tested in various catalytic enantioselective reactions, proving the purity of the product and its synthetic usefulness.     

Mild and efficient copper-catalyzed amination of aryl bromides with primary alkylamines

[reaction: see text] An efficient copper-catalyzed amination of aryl bromides with primary alkylamines was developed that uses commercially available diethylsalicylamide as the ligand. This amination reaction can be performed at 90 degrees C in good yield. A variety of functional groups are compatible with these reaction conditions. Preliminary results show that this reaction can be carried out under solvent-free conditions with comparable yields.     

Regioselective copper-catalyzed amination of bromobenzoic acids using aliphatic and aromatic amines

A chemo- and regioselective copper-catalyzed cross-coupling procedure for amination of 2-bromobenzoic acids is described. The method eliminates the need for acid protection and produces N-aryl and N-alkyl anthranilic acid derivatives in up to 99% yield. N-(1-Pyrene)anthranilic acid has been employed in metal ion-selective fluorosensing. Titration experiments showed that this pyrene-derived amino acid forms an equimolar complex with Hg(II) in water resulting in selective fluorescence quenching even in the presence of other metal ions such as Zn(II) and Cd(II).     

Transformations of electrophilic reagents in a diethyl phosphite-potassium carbonate-ethanol system

Transformations of alkyl halides, aldehydes, and activated alkenes in a (EtO)₂PHO−K₂CO₃−EtOH heterophase system were studied. The reactions are catalyzed by EtOK that formed and follow the known schemes of the interaction of hydrophosphoryl compounds with electrophiles. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 369–372, February, 1999.