N-Alkylation of poor nucleophilic amines and derivatives with alcohols by a hydrogen autotransfer process catalyzed by copper(II) acetate: scope and mechanistic considerations

Copper(II) acetate is a versatile, cheap and simple catalyst for the selective N-monoalkylation of amino derivatives with poor nucleophilic character, such as aromatic and heteroaromatic amines as well as carboxamides, phosphinamides, sulfonamides, and phosphazenes, using in all cases primary alcohols as initial source of the electrophiles, through a hydrogen autotransfer process. In the case of sulfonamides, the monoalkylation process followed by a naphthalene-catalyzed reductive deprotection gives primary amines, which is an indirect alternative to the direct monoalkylation of ammonia. A study of the reaction using deuterium labelled reagents was performed, indicating that the dehydrogenation and hydrogenation steps do not take placed on the same copper-atom coordination sphere, with the condensation step occurring out of the dehydrogenating catalytic species.     

Easy α-alkylation of ketones with alcohols through a hydrogen autotransfer process catalyzed by RuCl2(DMSO)4

The electrophilic α-alkylation of ketones with alcohols is accomplished by a hydrogen autotransfer process catalyzed by RuCl₂(DMSO)₄. The reaction can produce either simple alkylated ketones or α,β-unsaturated ketones just by choosing the appropriate starting ketones (methyl ketones or bicyclic methylenic ketones, respectively), as well as quinolines (by using 2-aminobenzyl alcohol derivatives) or the corresponding alcohol derivatives by the addition of an extra equivalent of the initial alcohol. In the last case, after the above alkylation process reduction of the carbonyl compound takes place. A mechanistic study seems to indicate that the process goes through the oxidation of the alcohols with ruthenium (after a previous deprotonation) to yield the corresponding aldehyde and a ruthenium hydride intermediate. In turn, the aldehyde suffers a classical aldol reaction with the starting ketone to form the corresponding α,β-unsaturated ketone, which finally is reduced through a Michael-type addition by the aforementioned ruthenium hydride intermediate.     

Palladium(II) chloride catalyzed selective acetylation of alcohols with vinyl acetate

PdCl(2) can catalyze the acetylation of primary and secondary alcohols with vinyl acetate. The reaction is selective and mild with high yields. Tertiary alcohols, phenols and amines are unaffected under these reaction conditions.     

RuCl2(DMSO)4 catalyzes the β-alkylation of secondary alcohols with primary alcohols through a hydrogen autotransfer process

The electrophilic β-alkylation of secondary alcohols with primary alcohols is accomplished by a hydrogen autotransfer process catalyzed by RuCl₂(DMSO)₄. The reaction can produce either simple alkylated secondary alcohols or α,β-unsaturated ketones with good to excellent results just by choosing the appropriate starting secondary alcohol (methyl or longer chain secondary alcohol, respectively), as well as quinolines (by using 2-aminobenzyl alcohol).     

Selective aqueous oxidation of alcohols catalyzed by copper (II) phthalocyanine nanoparticles

A new catalyst based on metallophthalocyanine nanoparticles has been synthesized and characterized by scanning electron microscopy (SEM). The aqueous oxidation of alcohols to the corresponding carbonyl compounds (aldehydes and ketones) has been studied using tetra-n-butyl-ammonium-peroxo-monosulfate (n-Bu₄NHSO₅) as an oxidant and a catalytic system consisting of copper (II) phthalocyanine nanoparticles in water. The highly selective oxidation gave excellent yields of related aldehydes or ketones without remarkable over-oxidation of the carboxylic acids. Organic co-solvents, surfactants, and co-catalysts were not used in this catalytic strategy. This strategy was green and time effective. The oxidant's by-product (TBAHSO₄) and catalyst can be efficiently recovered and reused several times without any significant change of catalytic activity.     

An efficient homogeneous gold(I) catalyst for N-alkylation of amines with alcohols by hydrogen autotransfer

A new and highly efficient homogeneous [Ph₃PAuCl]/AgOTf catalytic system was developed in N-alkylation reaction of primary amines with alcohols through a hydrogen autotransfer process. This Au(I) catalytic system shows excellent selectivity for mono-alkylation of primary amines with benzyl alcohol under moderate temperature of 100 °C (only secondary amines as product). The possible mechanism of this hydrogen autotransfer reaction with the catalytic system was proposed.     

Dehydration of alcohols catalyzed by copper(II) sulfate adsorbed on silica gel

Copper(II) sulfate adsorbed on silica gel efficiently dehydrated secondary and tertiary alcohols under mild conditions to give olefins. The rate of dehydration of tertiary alcohols is much faster than that of secondary alcohols.     

Direct C2-trifluoromethylation of indole derivatives catalyzed by copper acetate

Direct C2-selective trifluoromethylation of indole derivatives was achieved with Togni’s hypervalent iodine reagent and CuOAc as a catalyst in MeOH under mild conditions, affording the desired C2-trifluoromethylated indoles in good yield (up to 90%).     

Cobalt(II) catalyzed tosylation of alcohols with p-toluenesulfonic acid

Cobalt(II) chloride hexahydrate (CoCl₂·6H₂O) has been found to catalyze the tosylation of both aliphatic and aromatic alcohols with p-toluenesulfonic acid (p-TsOH) in high yields in 1,2-dichloroethane under reflux (ca. 80 °C). In the case of aliphatic alcohols, secondary alcohols undergo tosylation chemoselectively in the presence of primary hydroxy groups.     

Kinetic resolution of vic-amino alcohols catalyzed by a chiral Cu(II) complex

Kinetic resolution of N-benzoylated vic-amino alcohols was achieved by benzoylation in the presence of copper triflate and (R,R)-Ph-BOX as catalysts. The observed enantioselectivity was moderate to high. The method was applied to a kinetic resolution of racemic prolinol and piperidinemethanol derivatives as well as an asymmetric desymmetrization of 2-amino-1,3-diol derivatives.     

Alpha-(trifluoromethyl)amine derivatives via nucleophilic trifluoromethylation of nitrones

(Trifluoromethyl)trimethylsilane (TMSCF(3)) reacts with nitrones to afford alpha-(trifluoromethyl)hydroxylamines protected as O-trimethylsilyl ethers. Potassium t-butoxide initiates the nucleophilic trifluoromethylation. The reaction works best with alpha,N-diaryl nitrones, and the conditions are compatible with a range of substituents on the aryl groups. Acidic deprotection of the nitrone/TMSCF(3) adducts generates alpha-(trifluoromethyl)hydroxylamines. Catalytic hydrogenation of the adducts produces alpha-(trifluoromethyl)amines. Nitrone/TMSCF(3) adducts with strong electron-withdrawing groups on the alpha-aryl ring or heterocyclic alpha-aryl groups undergo an elimination/addition sequence to generate alpha,alpha-bis(trifluoromethyl)amines. Nitrones with alkyl groups bound directly to the 1,3-dipolar moiety fail to react with TMSCF(3), but trifluoromethylation of beta,gamma-unsaturated nitrones followed by reduction of the double bond can circumvent this limitation.     

Cobalt(II)–catalyzed C8H alkoxylation of 1-naphthylamine derivatives with alcohols

An efficient protocol for cobalt (II)-catalyzed regioselective aryl C8H bond alkoxylation of 1-naphthylamine derivatives with readily available alcohols has been developed, demonstrating an efficient approach to 8-alkoxy-1-naphthylamine derivatives with good functional group tolerance. Note that the picolinamide moiety as a bidentate directing group may play a key role in this regioselective transformation.     

Efficient solvent-free iron (III) catalyzed oxidation of alcohols by hydrogen peroxide

Selective oxidation of secondary and benzylic alcohols was efficiently accomplished by H₂O₂ under solvent-free condition catalyzed by FeBr₃. Secondary alcohols are selectively oxidized even in the presence of primary ones. This method is high yielding, safe and operationally simple.     

Enantioselective copper(II)‐catalyzed Henry reaction utilizing chiral aziridinyl alcohols

A family of enantiopure β‐aminoalcohols based on aziridine backbones were synthesized, and examined as chiral ligands for the copper(II)‐catalyzed asymmetric Henry reaction of aromatic aldehydes with nitromethane, giving β‐nitroalcohols in excellent yields (up to 93%) and moderate to good enantioselectivities (up to 82%). Moreover, possible transition states of the reaction are proposed. Copyright © 2014 John Wiley & Sons, Ltd.     

The kinetics and mechanism of homogeneous hydrogen transfer from alcohols to benzylideneacetone catalyzed by dichlorotris(triphenylphosphine)ruthenium(II)

Dichlorotris(triphenylphosphine)ruthenium(II) catalyzes the hydrogen transfer from alcohols to olefins. Kinetic studies were carried out at 170–190°C using the ruthenium(II) complex as homogeneous catalyst, benzyl alcohol, diphenylcarbinol, methylphenylcarbinol and benzoin as the hydrogen donors, benzylideneacetone as the hydrogen acceptor, and dibenzyl ether as a solvent. The IR spectra and GLC were used to monitor the reaction and the isotope effects were determined in order to elucidate the role of the catalyst and the mechanism of hydrogen transfer. In the reaction mixture RuCl₂(PPh₃)₃ is converted by the alcohols into RuH₂(CO) (PPh₃)₃, which then hydrogenates benzylideneacetone. The kinetic data are compatible with the expression. reaction rate = k_obs[Ru][olefin][alcohol] The rate-determining step of this reaction is considered to be the transfer of hydrogen from the alcohol to a ruthenium species.     

One-pot synthesis of tetrahydrofuran derivatives from allylic alcohols and vinyl ethers by means of palladium(II) acetate

Treatment of a mixture of allylic alcohol and vinyl ether in the presence of Pd(OAc)₂ provides 2-alkoxy-4-alkenyltetrahydrofuran in good yield.     

Epoxidation of alkenes and oxidation of alcohols with hydrogen peroxide catalyzed by a manganese(V) nitrido complex

The manganese(V) nitrido complex (PPh(4))(2)[Mn(N)(CN)(4)] is an active catalyst for alkene epoxidation and alcohol oxidation using H(2)O(2) as an oxidant. The catalytic oxidation is greatly enhanced by the addition of just one equivalent of acetic acid. The oxidation of ethene by this system has been studied computationally by the DFT method.     

Thermogravimetric investigation of some mononuclear and binuclear complexes of copper(II) acetate with pyridine derivatives

Binuclear complexes of the type Cu₂(CH₃CO₂)₄L₂ (L=pyridine, 2-chloropyridine, 3-chloropyridine, 2,4-dimethylpyridine, 3,4-dimethylpyridine, isoquinoline) and mononuclear complexes of the type Cu(CH₃CO₂)₂Py₃, Cu(CH₃CO₂)₂Py₃H₂O, Cu(CH₃CO₂)₂(3,4-Lut)₂H₂O have been investigated by thermogravimetry. A linear correlation is shown to exist between the pK_a of the base ligand and the thermal stability of the corresponding binuclear complexes as determined from the thermal analysis data. The results show that the tendency to eliminate the base ligand from these complexes decreases with decreasing basicity of the substituted pyridine. The strong steric effect associated with -substituted pyridine ligands on the decomposition temperatures of the corresponding complexes is noted.

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Zusammenfassung Binukleare Komplexe des Typs Cu₂(CH₃CO₂)₄L₂ (L=Pyridin, 2-Chlorpyridin, 3-Chlorpyridin, 2,4-Dimethylpyridin, 3,4-Dimethylpyridin, Isoquinolin) und mononukleare Komplexe des Typs Cu(CH₃CO₂)₂Py₃, Cu(CH₃CO₂)₂Py₃ · H₂O und Cu(CH₃CO₂)₂(3,4-Lut)₂·H₂O werden thermogravimetrisch untersucht. Aus den thermoanalytischen Daten ergibt sich eine lineare Korrelation zwischen denpK _a Wert der basischen Liganden und der thermischen Stabilität der entsprechenden binuklearen Komplexen. Die Tendenz zur Eliminierung der basischen Liganden dieser Komplexe nimmt mit abnehmender Basizität der substituierten Pyridine ab. Auf den beträchtlichen, mit dem-substituierten Pyridinliganden zusammenhängenden sterischen Effekt auf die Zersetzungstemperature der entsprechenden Komplexes wird hingewiesen.

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Cu₂(CH₃CO₂)₄L₂ (L=, 2- 3- , 2,4- 3,4- ), Cu(CH₃COO)₂Py₃, Cu(CH₃COO),Py₃·H₂O Cu(CH₃COO)₂(3,4-)₂ · H₂O. pK _a . , . ga- .

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Presented at the International Summer School of Calorimetry and Thermal Analysis, Belgirate, Italy; October 1–5, 1984.

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The financial support of the Polish Academy of Sciences is gratefully acknowledged. We are also indebted to Dr Pielak for analysing the sintered products.     

Dehydrative glycosylation of tri-O-benzylated 1-hydroxyribofuranose catalyzed by a copper(II) complex

A phosphine/Cu(II) complex catalyzes the dehydrative glycosylation of tri-O-benzylated 1-hydroxyribofuranose to give the ribofuranoside with high stereoselectivity.     

Alkylation of cyclic amines with alcohols catalyzed by Ru(II) complexes bearing N-Heterocyclic carbenes

This paper includes the synthesis of 2-(1,3-dioxane-2-yl)ethyl substituted benzimidazole substituted N-heterocyclic carbenes precursors and their ruthenium complexes. Synthesized compounds were characterized by elemental analysis and NMR spectroscopy. All complexes have been tested in the alkylation of pyrrolidine and morpholine with alcohols, showing an excellent activity in this reaction.