One-pot β-alkylation of secondary alcohols with primary alcohols catalyzed by ruthenacycles

A ruthenacycle-catalyzed one-pot β-alkylation of secondary alcohols with primary alcohols is described. A survey of four C–N chelate ruthenacycles synthesized via the cyclometallation reaction of phenylmethanamine, N-methylphenylmethanamine, N,N-dimethylphenylmethanamine, and naphthalen-1-ylmethanamine with [(η⁶-C₆H₆)RuCl₂]₂ was undertaken. All four complexes were found to be active with the phenylmethanamine-based ruthenacycle showing the best combination of reactivity and product selectivity among the four. An expanded scope of substrates was also studied with the inclusion of unsaturated primary alcohols. The reactivity trend observed gave insights into the role of hydrogen bonding in the catalytic mechanism involving transfer hydrogenation between the substrates and the transition metal catalyst.     

Synthesis of axially chiral oxazoline–carbene coordinated palladium complexes with a N-phenyl framework

A family of tropos ligands bearing a N-heterocyclic carbene and a chiral oxazoline coordination group with a N-phenyl framework were easily prepared,and their coordination behavior with Pd(Ⅱ)acetate was performed,affording a series of axially chiral palladium complexes in good yields.     

Polymerization of 5-norbornene-2-methyl acetate catalyzed by air-stable cationic (η-substituted allyl) palladium complexes of N-heterocyclic carbene

In situ generated cationic (η³-substituted allyl) palladium N-heterocyclic carbene (NHC) complexes are air-stable active catalysts for the olefin polymerization of (bicyclo[2.2.1]hept-5-en-2-yl)methyl acetate (5-norbornene-2-methyl acetate) (endo:exo = 7:3). Catalytic activities, polymer yields, molecular weights, and molecular weight distributions of polymers were investigated under various reaction conditions. The catalytic activity was highly dependent not only on the reaction condition such as a solvent or the reaction temperature but also on the structure of the catalyst that include substituents of the allyl group in the catalyst and the counter anion. As the bulkiness of the allyl group increased, the catalytic activity of the catalysts increased.     

Inclusion complexes of alcohols with α-cyclodextrin

Calorimetric studies of the inclusion complexes of straight and branched alcohols and of diols with alpha-cyclodextrin (-CD) have been carried out in water solvent. The data suggest that straight and branched chain alcohols enter the cavity of -CD alkyl end first. The hydroxyl group hydrogen bonds to the outer oxygen ring of the cyclodextrin. For branched chain alcohols the longer alkyl part of the molecule penetrates the -CD cavity up to the hydroxyl group. Diols form two hydrogen bonds to the outer oxygen ring of the cyclodextrin with some penetration into its interior.     

Cyclomagnesation of cycloalkynes with the use of RMgR’ catalyzed by zirconium complexes

The intermolecular cyclomagnesation of cycloalkynes and joint cyclomagnesation of cycloalkynes and disubstituted acetylenes was carried out by treating with RMgR′ (R, R′ = Et, Bu, Hlg) in the presence of Cp₂ZrCl₂ as a catalyst. As a result new unsaturated bi-and tricyclic organomagnesium compounds were obtained in high yields.     

Heterogeneous oxidation of alcohols with hydrogen peroxide catalyzed by polyoxometalate metal–organic framework

HSiW-MOF, PMo-MOF, HPMo-MOF and PW-MOF were synthesized and characterized by elemental analysis, UV–Vis, FT-IR, cyclic voltammetry and XRD. These compounds were used as catalyst for the selective oxidation of alcohols by hydrogen peroxide. Within them, PW-MOF showed a higher catalytic activity compared to other catalysts in a similar reaction condition. Therefore, PW-MOF catalyst system was successfully used for the selective oxidation of the benzylic, linear and secondary alcohols to the corresponding aldehydes and ketones. Also, allylic alcohols were converted to the corresponding aldehydes with high conversion and significant selectivity. Moreover, PW-MOF was stable to leaching, behaved as true heterogeneous catalysts, easily recovered by filtration, and reused four times with the preserve of the catalytic performance.     

Direct α-alkylation of ketones with primary alcohols catalyzed by iridium–CNP complex

The α-alkylation of ketones with primary alcohols was realized by CC cross-coupling with iridium–CNP complexes as catalyst. This reaction proceeds via dehydrogenation reactions, aldol condensation, and hydrogenation using the borrowed hydrogen atoms from alcohols. The pyridyl methanols and other heterocyclic substituted methanols, especially alkyl alcohols, were also suitable for this transformation.     

Synthesis of β-amino alcohols catalyzed by poly(vinyl chloride)-supported Schiff base metal complexes

Abstract  

Eight transition metal complexes of various Schiff bases supported on poly(vinyl chloride) (PVC) were prepared and characterized. These metal complexes were screened as heterogeneous catalysts in the synthesis of β-amino alcohols by ring opening of epoxides with amines. The best catalyst was identified as a Ni(II) complex of PVC-supported 2-[(2-aminoethylimino)methyl]phenol and it was used in the synthesis of a number of different β-amino alcohols. The catalyst was found to be reusable for up to five cycles.     

Selective reactivity of electron-rich aryl iodides in the Heck arylation of disubstituted alkenes catalyzed by palladium–arylurea complexes

A catalyst consisting of 1 mol % of the 1:2 complex of Pd(OAc)₂ with N-(4-carbethoxyphenyl)urea promotes the Heck arylation of 2- or 3-substituted, conjugated esters, nitriles, aldehydes, and ketones (an uncharacteristically broad range of substrates), but only with electron-rich aryl iodides (an uncharacteristically narrow range of halides).     

A new route of the reaction of EtAlCl2 with α-olefins catalyzed by Ti complexes

A new method for the synthesis of dialkyl(ethyl)alanes by the reaction of EtAlCl₂ with -olefins in the presence of Mg and a catalytic amount of Cp₂TiCl₂ (Ti(OPrⁱ)₄, Ti(OBuⁿ)₄) in THF was developed.     

Synthesis of β-amino alcohols by ring opening of epoxides with amines catalyzed by cyanuric chloride under mild and solvent-free conditions

Abstract

The 2,4,6-trichloro-1,3,5-triazine catalyzed synthesis of β-amino alcohols by aminolysis of epoxide under solvent-free condition is described. Mild reaction conditions, short reaction times, inexpensive and readily available catalysts, and excellent yields of the products with high regioselectivity are attractive features of this methodology.     

Efficient synthesis of β-amino alcohols by regioselective ring opening of epoxides with amines catalyzed by CuFe2O4 nanoparticles

A simple and efficient method has been developed for the synthesis of β-amino alcohols by regioselective ring opening of epoxides with amines in the presence of CuFe₂O₄ nanoparticles as a heterogeneous recyclable catalyst at room temperature in high yields.     

Regioselective tetrahydropyranylation of alcohols catalyzed by Fe（HSO4）3

Alcohols are selectively and efficiently protected as their tetrahydropranyl ethers in the presence of a catalytic amount of Fe(HSO4)3 in good to high yields. All reactions are performed under mild and completely heterogeneous reaction conditions.     

Development and outlook of chiral carbene–gold(I) complexes catalyzed asymmetric reactions

Great progress has been made in developing of homogeneous Au-catalyzed reactions in the past decade. The unique versatility and efficiency of gold complexes have been obtained including carbene ligated gold complexes. Due to the special linear coordination mode of gold(I) complex, Au catalyzed asymmetric reactions have become a huge challenge. Chiral carbene–gold complexes also have been applied in asymmetric reactions. Major breakthrough in this field has been obtained by the Toste group recently and more are expected in the future. This digest, by highlighting recent works, aims to make further progress in this fascinating research field.     

Enantioselective alkylation of benzaldehyde with diethylzinc catalyzed by 1,1′- and 1,2-disubstituted ferrocenyl amino alcohols

Optically active 1,1′- and 1,2-disubstituted ferrocenyl amino alcohols have been synthesized from 1,1′- and 1,2-ferrocene dicarboxaldehyde. They have been used as chiral catalysts in the asymmetric addition of diethylzinc to benzaldehyde. 1-Phenylpropanol has been obtained in up to 83% enantiomeric excess.     

Homocoupling of benzyl halides catalyzed by POCOP–nickel pincer complexes

Two types of POCOP–nickel(II) pincer complexes were prepared by mixing POCOP pincer ligands and NiX₂ in toluene at reflux. The resulting nickel complexes efficiently catalyze the homocoupling reactions of benzyl halides in the presence of zinc. The coupled products were obtained in excellent to quantitative yields.     

Asymmetric hydrocyanation of olefins catalyzed by chiral diphosphite–nickel complexes

Chiral aryl diphosphite ligands derived from binaphthol were found to be effective in the nickel-catalyzed hydrocyanation of a variety of olefins. Enantioselective hydrocyanations of styrene, 4-substituted styrenes and norbornene were achieved with excellent regioselectivity and moderate enantioselectivity. The hydrocyanation of vinyl acetate gave 72.9% ee. The catalytic activity and the enantioselectivity of the Ni(0)–diphosphite complexes were found to be highly dependent on the structures of the ligands.     

Efficient synthesis of diversely substituted pyrimidines by palladium catalyzed Suzuki–Miyaura coupling

An efficient synthesis of 2-aryl/heteroaryl substituted pyrimidinyl ethanones 4(a–t) was developed using a palladium-catalyzed Suzuki–Miyaura coupling reaction strategy. Use of Pd(OAc)₂ in the presence of PPh₃ and Na₂CO₃ in 1,4-dioxane solvent was found to be the most effective reaction condition.