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A large family of phosphite‐thioether/selenoether ligands has been easily prepared from accessible L‐(+)‐tartaric acid and D‐(+)‐mannitol and applied in the M‐catalyzed (M=Ir, Rh) asymmetric hydrogenation of a broad number of substrates (46 in total). Its highly modular architecture has been crucial to maximize the catalytic performance. Improving most of the reported approaches, this ligand family presents a broad substrate scope. By selecting the ligand parameters high enantioselectivities (ee's up to 99 %) have therefore been achieved in a broad range of both, functionalized and unfunctionalized substrates. Interestingly, both enantiomers of the hydrogenation products can be usually achieved by changing the ligand parameters. [ABSTRACT FROM AUTHOR]

A series of seven novel NImNHP-type pincer imidazolylphosphine ruthenium complexes has been synthesized and fully characterized. The use of hydrogenation of benzonitrile as a benchmark test identified [RuHCl(CO)(NImNHP tBu)] as the most active catalyst. With its stable Ru−BH4 analogue, in which chloride is replaced by BH4, a broad range of (hetero)aromatic and aliphatic nitriles, including industrially interesting adiponitrile, has been hydrogenated under mild and base-free conditions. [ABSTRACT FROM AUTHOR]

The mechanism of acetonitrile and methyl benzoate catalytic hydrogenation using pincer catalysts M(H)2(CO)[NH(C2H4P iPr2)2] ( 1M) and M(H)(CO)[N(C2H4P iPr2)2] ( 2M) (M = Fe, Ru, Os) has been computed at various levels of density functional theory. The computed equilibrium between 1Fe and 2Fe agrees perfectly with the experimental observations. On the basis of the activation barriers and reaction energies, the best catalysts for acetonitrile hydrogenation are 1Fe/2Fe and 1Ru/2Ru, and the best catalysts for methyl benzoate hydrogenation are 1Ru/2Ru. The best catalysts for the dehydrogenation of benzyl alcohol are 1Ru/2Ru. It is to note that the current polarizable continuum model is not sufficient in modeling the solvation effect in the energetic properties of these catalysts as well as their catalytic properties in hydrogenation reaction, as no equilibrium could be established between 1Fe and 2Fe. Comparison with other methods and procedures has been made. © 2015 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

We present the first base-free Fe-catalyzed ester reduction applying molecular hydrogen. Without any additives, a variety of carboxylic acid esters and lactones were hydrogenated with high efficiency. Computations reveal an outer-sphere mechanism involving simultaneous hydrogen transfer from the iron center and the ligand. This assumption is supported by NMR experiments. [ABSTRACT FROM AUTHOR]

Abstract: The ligand design of one of the most successful monophosphite ligand classes in Rh-catalyzed hydrogenation was expanded upon by introducing several substituents at the C-3 position of the furanoside backbone. A small but structurally important library of monophosphite ligands was developed by changing the substituents at the C-3 position of the furanoside backbone and the substituents/configurations at the biaryl phosphite group. These new furanoside monophosphite ligands were evaluated in the Rh-catalyzed asymmetric hydrogenation of α,β-unsaturated carboxylic acid derivatives and enamides. The results show that the effect of introducing a substituent at the C-3 position of the furanoside backbone on the enantioselectivity depends not only on the configuration at the C-3 position of the furanoside backbone and the binaphthyl group but also on the substrate. Thus, the new ligands afforded high to excellent enantioselectivities in the reduction of carboxylic acid derivatives (ee’s up to >99.9%) and moderate ee’s (up to 67%) in the hydrogenation of enamides. [Copyright &y& Elsevier]

Unknown 1 H-2,7-dihydro-1-phenylphosphepine, containing a 2,2′,5,5′-tetramethyl-3,3′-bithiophene atropisomeric scaffold (Ph-tetraMe-Bithienine), and its oxide have been synthesized and structurally characterized by single-crystal X-ray diffraction analysis. The most evident structural feature is the very small dihedral angle. The electronic properties of the phosphane were quantitatively evaluated by cyclic voltammetry and compared with three other 2,7-dihydro-1-phenylphosphepines differing in the nature of the biaromatic scaffold (biphenyl, 1,1′-binaphthyl and 2,2′-dimethoxybiphenyl). The racemate of the phosphane oxide was resolved into antipodes, which were reduced to the enantiopure phosphanes and employed as ligands in Rh and Pt complexes in homogeneous stereoselective catalytic reactions. The enantioselective ability and catalytic activity of the new mediators were found to be quite modest in the hydrogenation reactions of olefinic double bonds, whereas good performances were achieved in specific C-C bond-forming reactions. The results are interpreted on the basis of the steric and electronic properties of the ligand. [ABSTRACT FROM AUTHOR]

A novel class of the title pincer complexes is designed and the BH4-derivative (NPR) is used as catalyst for the highly efficient hydrogenation of a variety of nitriles to the corresponding amines. [ABSTRACT FROM AUTHOR]

A broad range of secondary and tertiary amides is hydrogenated to the corresponding amines under mild conditions using an in situ catalyst generated by combining [Ru(acac)3], 1,1,1-tris(diphenylphosphinomethyl)ethane (Triphos) and Yb(OTf)3. [ABSTRACT FROM AUTHOR]

By introducing substituents at the C-3 position of the furanoside moiety novel furanoside monophosphite ligands having a BINOL-phosphite substituent are developed and their ability as ligand in asymmetric Rh-catalyzed hydrogenation reactions is successfully examined. [ABSTRACT FROM AUTHOR]

A planar-chiral diphosphine ligand-class based on an arene chromium tricarbonyl backbone has been devised featuring a modular architecture that allows for the synthesis of a broad ligand library. The substituents on the donor phosphorus atoms contain aliphatic, alicyclic and aromatic groups of different kinds. A (R,R)-2,5-dimethylphospholane moiety is also included. That library has been subdued to a ligand profiling by employment in a number of homogeneous enantioselective hydrogenations including substrates with CC, CN and CO double bonds. These reactions are described and the results are evaluated and discussed. [Copyright &y& Elsevier]

The process involves a base-free reduction in the presence of the novel iron complex AIPC without any additives. [ABSTRACT FROM AUTHOR]

The title ligand is synthesized and its utility for Rh-catalyzed asymmetric hydrogenations as well as for the alkoxycyclization of enyne (V) is demonstrated. [ABSTRACT FROM AUTHOR]