Copper(II) Triflate–Mediated Addition Reaction of α‐Oxygenated Alkylsilanes to Imines for the Synthesis of Vicinal‐Amino Alcohols

In the presence of copper(II) triflate, the addition reaction of α‐oxygenated alkylsilanes to several imines proceeded smoothly to give the corresponding vicinal‐amino alcohols in moderate yields.     

First example of the coupling of α-diazoketones with thiourea: a novel route for the synthesis of 2-aminothiazoles

α-Diazoketones undergo smooth coupling with thiourea in the presence of 10 mol % of copper(II) triflate to produce the corresponding 2-aminothiazoles in excellent yields with high selectivity. The use of copper(II) triflate makes this method simple, convenient and practical. This method works well with both aryl and alkyl diazoketones to furnish a wide range of 2-aminothiazoles.     

Diastereoselective synthesis of strained spiro-cyclopropanooxindoles from cyclic diazoamides

Reaction of cyclic diazoamides and cyclic olefins or heteroaromatic systems using copper(I) triflate as a catalyst furnished a variety of strained spiro-cyclopropanooxindoles in a diastereoselective manner under mild reaction conditions. The effect of copper(I) triflate and rhodium(II) acetate catalysts on the cyclopropanation was also studied.     

Copper(I)-catalysed homo-coupling of aryldiazonium salts: synthesis of symmetrical biaryls

Copper(I) triflate acts as an efficient stoichiometric reagent for the homo-coupling of aryldiazonium salts bearing electron-withdrawing group(s), to yield symmetrical biaryls in acetonitrile under mild reaction conditions. Aryldiazonium salts bearing electron-donating groups undergo the reaction by using catalytic amounts of a copper complex prepared in situ from copper(II) triflate and 2,2′-bipyridine with metallic copper as an ultimate reductant.     

A single Cu(II) catalyst for the three-component coupling of diverse nitrogen sources with aldehydes and alkynes

A single Cu(II) catalyst without the addition of ligand or base couples a diverse range of nitrogen sources with alkynes and aldehydes bearing alkyl, halogenated, silyl, aryl, and heteroaryl groups. The first example of a copper-catalyzed alkynylation involving p-toluenesulfonamide provides high yields of N-Ts-protected propargylamines. The superior activity of copper(II) triflate also allows this three-component alkynylation to incorporate a ketone.     

三氟甲基磺酸铜(II)手性衍生物:不对称合成中的一类高效催化剂

三氟甲基磺酸铜 [Cu(OTf) 2 ]与各种手性磷氮配体络合催化不对称合成已取得了巨大进展 .详细评述了近五年来该类手性铜催化剂在各种不对称催化反应中的最新应用     

Catalytic enantioselective addition of dialkylzinc to N-diphenylphosphinoylimines. A practical synthesis of alpha-chiral amines

The enantioselective addition of dialkylzinc reagents to N-diphenylphosphinoylimines derived from aryl-, furyl-, and cyclopropylaldehydes is efficiently catalyzed by a copper(II) triflate/(R,R)-MeDUPHOS complex. The yields are high (51-98%), and the enantiomeric excesses vary from 85 to 96%. This route provides a practical route to alpha-chiral amines.     

Copper(II) Triflate,a New Reagent for Mild Dehydration of Alcohols: Synthetic Usefulness and Mechanistic Insight

The effectiveness of copper(II) triflate (copper(II) trifluoromethanesulfonate) as a new dehydrating reagent for a variety of alcohols has been demonstrated. Based on several control experiments, a possible mechanism is suggested.     

Copper(II)/phenanthroline-mediated CD-enhancement and chiral memory effect on a meta-ethynylpyridine oligomer

meta-Ethynylpyridine 18-mer associates with octyl β-D-glucopyranoside to show an induced circular dichroism (CD) band at around 337 nm in CH(2)Cl(2). The addition of copper(II) triflate and o-phenanthroline enhanced the CD band. Even when an equimolar amount of β-L-glucopyranoside was added to make the system racemic, the CD was memorized and remained for several weeks.     

Asymmetric Diels—Alder Reaction Catalyzed by Novel Chiral Dibenzo[a,c] cycloheptadiene Bis（oxazoline） Metal Complexes

A series of novel chiral C2-symmetric bis (oxazoline) ligands have been synthesized.The copper and magnesium complexes,prepared in situ from copper(Ⅱ)-triflate of magnesium triflate with the new enantiopure oxazoline ligands,were evaluated as chiral catalysts in the enantioselective Diels-Alder reaction of cyclopentadiene with N-crotenoyl-oxazolidin-2-one.Primary results showed that diastereoselectivity up to 94% and enantioselectivity up to 68% ee for endo products were observed respectively with these ligands.     

The influence of metal(II) salts and solid supports on the nature of the photochemical reaction of 1,1-diphenyl-2-haloethene

Photolysis of 1,1-diphenyl-2-haloethene in methanol solution in the presence of copper(II) acetate, copper(II) triflate or cadmium(II) acetate results in the formation of ionic and radical products. The ratio of ionic to ionic and radical products depends on the halogen atom and the salt used. The effect of a solid support (silica gel, silica gel impregnated with copper(II) or cadmium(II) salts) was studied and it was found that the product distribution and the ratio of ionic to ionic and radical products are different from the results obtained during irradiation in solution.     

Enantioselective conjugate addition of diethylzinc to cyclohexenone catalyzed by a chiral aminophosphine–copper(II) triflate

Enantioselective conjugate addition of diethylzinc to cyclohexenone and 4,4-dimethylcyclohexenone was catalyzed by the combination of 0.1 equiv. of a chiral monodentate aminophosphine 3 and 0.05 equiv. of copper(II) triflate to give the corresponding adducts 4 in up to 70% ee.     

Conjugate addition of indoles to α,β-unsaturated ketones using Cu(OTf)2 immobilized in ionic liquids

Indoles undergo smooth conjugate addition with α,β-unsaturated ketones in the presence of 10 mol% copper(II) triflate immobilized in air and moisture stable [bmim]BF₄ ionic liquid under mild conditions to afford the corresponding conjugate addition products in high to quantitative yields. The recovery of Cu(OTf)₂ is facilitated by the ionic liquid. The recovered catalyst was reused four to five times with consistent activity.     

Tin-free intermolecular addition of primary alkyls to imines via the dimethylzinc-air radical process

[reaction: see text] A dimethylzinc-air initiator was applied to the generation of primary alkyl radicals from alkyl iodides. The addition of the generated primary alkyl radicals to N-tosylimines was accelerated by the action of boron trifluoride-diethyl etherate and copper(II) triflate to give the corresponding adducts in good yields after 2-3 h. Air oxygen was essential for the reaction to proceed, showing involvement of a radical process in the reaction.     

Complex formation of copper(II) and palladium(II) with L,L-3,7-bis[2-(4-hydroxyphenyl)-1-(methoxycarbonyl)ethyl]-1,5-di(ethoxycarbonyl)-3,7-diazabicyclo[3.3.1]nonan-9-one

Complexation of copper(II) chloride, copper(II) triflate, and palladium(II) chloride with optically active L,L-3,7-bis[2-(4-hydroxyphenyl)-1-(methoxycarbonyl)ethyl]-1,5-di(ethoxycarbonyl)-3,7-diazabicyclo[3.3.1]nonan-9-one was studied.     

Oxidative radical cyclisations for the synthesis of gamma-lactones

The use of manganese(III) acetate in combination with copper(II) triflate allows the synthesis of [3.3.0]-bicyclic gamma-lactones from 4-pentenylmalonates in excellent yields.     

C(2) symmetric chiral NHC ligand for asymmetric quaternary carbon constructing copper-catalyzed conjugate addition of grignard reagents to 3-substituted cyclohexenones

The asymmetric construction of quaternary carbon centers by conjugate addition of Grignard reagents to 3-methyl- and 3-ethylcyclohexenones was realized in a maximum enantioselectivity of 80% by using a C 2 symmetric chiral N-heterocyclic carbene (NHC)-copper catalyst, generated from (4 S,5 S)-1,3-bis(2-methoxyphenyl)-4,5-diphenyl-4,5-dihydro-1 H-imidazol-3-ium tetrafluoroborate and copper(II) triflate. The stereostructures of the NHC-Au complexes were analyzed by X-ray crystallography, which rationalized the good stereocontrolling ability of N-aryl NHCs.     

Cu(I)- and Cu(II)-catalyzed cyclo- and Michael addition reactions of unsaturated β-ketoesters

The α-alkylidene β-ketoesters 2-carbethoxycyclopentenone (1a) and ethyl 2-benzoylacrylate (1b) react with 1,2-dimethylbutadiene (2) (Diels-Alder), N-benzyl-N-(cyclohexylethynyl)-4-methylbenzenesulfonamide (3) (Ficini reaction), ethynyl(phenyl)sulfane (4) ([2 + 2] cycloaddition), and 1,2,5-trimethyl-1H-pyrrole (5) (Michael addition) in the presence of copper(I) (6) or copper(II) triflate (7) (1-2 mol %) in dichloromethane. This convenient protocol converts 1a and 1b to the corresponding cycloaddition (8-10) or Michael addition (11) products in good yields after reaction times of 0.5-3 h without requiring purified solvents or inert gas atmosphere.     

A tandem reaction of 2-alkynylbenzaldoximes with cyclic ethers co-catalyzed by silver(I) triflate and copper(II) acetate

A tandem reaction of 2-alkynylbenzaldoximes with cyclic ethers co-catalyzed by silver(I) triflate and copper(II) acetate is developed, affording 1-substituted isoquinolines in moderate to good yields. The transformation proceeds efficiently through C–H activation.     

Copper-catalyzed reaction of alkyl halides with cyclopentadienylmagnesium reagent

Treatment of alkyl halides, including tertiary alkyl bromides, with cyclopentadienylmagnesium bromide in the presence of a catalytic amount of copper(II) triflate yielded the corresponding cyclopentadienylated products in high yields. The following hydrogenation of the products provided alkyl-substituted cyclopentanes.