Highly selective Suzuki reaction catalysed by a molecular Pd–P-MOF catalyst under mild conditions: role of ligands and palladium speciation

A phosphine-functionalized MOF was used to prepare molecularly-defined palladium catalysts, active for Suzuki coupling in mild conditions. Their selectivity was correlated with the nature of the catalytic active site via XAS and NMR.

A State-of-the-Art Heterogeneous Catalyst for Efficient and General Nitrile Hydrogenation

Cobalt-doped hybrid materials consisting of metal oxides and carbon derived from chitin were prepared, characterized and tested for industrially relevant nitrile hydrogenations. The optimal catalyst supported onto MgO showed, after pyrolysis at 700 °C, magnesium oxide nanocubes decorated with carbon-enveloped Co nanoparticles. This special structure allows for the selective hydrogenation of diverse and demanding nitriles to the corresponding primary amines under mild conditions (e.g. 70 °C, 20 bar H₂ ). The advantage of this novel catalytic material is showcased for industrially important substrates, including adipodinitrile, picolinonitrile, and fatty acid nitriles. Notably, the developed system outperformed all other tested commercial catalysts, for example, Raney Nickel and even noble-metal-based systems in these transformations.

Asymmetric Hydrogenation of Unfunctionalized Tetrasubstituted Acyclic Olefins

Asymmetric hydrogenation has evolved as one of the most powerful tools to construct stereocenters. However, the asymmetric hydrogenation of unfunctionalized tetrasubstituted acyclic olefins remains the pinnacle of asymmetric synthesis and an unsolved challenge. We report herein the discovery of an iridium catalyst for the first, generally applicable, highly enantio- and diastereoselective hydrogenation of such olefins and the mechanistic insights of the reaction. The power of this chemistry is demonstrated by the successful hydrogenation of a wide variety of electronically and sterically diverse olefins in excellent yield and high enantio- and diastereoselectivity.

Chemoselective semihydrogenation of alkynes catalyzed by manganese(i)-PNP pincer complexes

A first homogeneous manganese catalyzed chemoselective semihydrogenation of alkynes to Z-olefins in the presence of molecular hydrogen is described.

A robust iron catalyst for the selective hydrogenation of substituted (iso)quinolones

By applying N-doped carbon modified iron-based catalysts, the controlled hydrogenation of N-heteroarenes, especially (iso)quinolones, is achieved. Crucial for activity is the catalyst preparation by pyrolysis of a carbon-impregnated composite, obtained from iron(ii) acetate and N-aryliminopyridines. As demonstrated by TEM, XRD, XPS and Raman spectroscopy, the synthesized material is composed of Fe(0), Fe3C and FeN x in a N-doped carbon matrix. The decent catalytic activity of this robust and easily recyclable Fe-material allowed for the selective hydrogenation of various (iso)quinoline derivatives, even in the presence of reducible functional groups, such as nitriles, halogens, esters and amides. For a proof-of-concept, this nanostructured catalyst was implemented in the multistep synthesis of natural products and pharmaceutical lead compounds as well as modification of photoluminescent materials. As such this methodology constitutes the first heterogeneous iron-catalyzed hydrogenation of substituted (iso)quinolones with synthetic importance.

Sterically Congested 2,6-Disubstituted Anilines from Direct C-N Bond Formation at an Iodine(III) Center

2,6‐Disubstituted anilines are readily prepared from the direct reaction between amides and diaryliodonium salts. As demonstrated for 24 different examples, the reaction is of unusually broad scope with respect to the sterically congested arene and the nitrogen source, occurs without the requirement for any additional promoter, and proceeds through a direct reductive elimination at the iodine(III) center. The efficiency of the coupling procedure is further demonstrated within the short synthesis of a chemerin binding inhibitor.

Correction: A robust iron catalyst for the selective hydrogenation of substituted (iso)quinolones

Correction for ‘A robust iron catalyst for the selective hydrogenation of substituted (iso)quinolones’ by Basudev Sahoo et al., Chem. Sci., 2018, DOI: ; 10.1039/c8sc02744g.

Asymmetric Synthesis of Akt Kinase Inhibitor Ipatasertib

A highly efficient asymmetric synthesis of the Akt kinase inhibitor ipatasertib (1) is reported. The bicyclic pyrimidine 2 starting material was prepared via a nitrilase biocatalytic resolution, halogen-metal exchange/anionic cyclization, and a highly diastereoselective biocatalytic ketone reduction as key steps. The route also features a halide activated, Ru-catalyzed asymmetric hydrogenation of a vinylogous carbamic acid to produce α-aryl-β-amino acid 3 in high yield and enantioselectivity. The API was assembled in a convergent manner through a late-stage amidation/deprotection/monohydrochloride salt formation sequence.

Manganese(I)-Catalyzed Enantioselective Hydrogenation of Ketones Using a Defined Chiral PNP Pincer Ligand

A new chiral manganese PNP pincer complex is described. The asymmetric hydrogenation of several prochiral ketones with molecular hydrogen in the presence of this complex proceeds under mild conditions (30-40 °C, 4 h, 30 bar H₂ ). Besides high catalytic activity for aromatic substrates, aliphatic ketones are hydrogenated with remarkable selectivity (e.r. up to 92:8). DFT calculations support an outer sphere hydrogenation mechanism as well as the experimentally determined stereochemistry.

Synthesis of Atropisomeric MeOBIPHEP Analogues and Their Application in Silver-Catalyzed Cycloisomerization of Allenols

The preparation of novel MeOBIPHEP atropisomeric chiral congener ligands via an efficient palladium-catalyzed P–C coupling key step is described. We demonstrate that these palladium-catalyzed conditions are compatible with the brominated MeOBIPHEP backbone. The reaction conditions for asymmetric silver-catalyzed cycloisomerization of γ-allenols were optimized, leading to the first enantioselective catalytic system employing atropisomeric diphosphine ligands as the chiral inducer. The process follows a major 5-exo cyclization via addition of the alcohol moiety to the π-activated allenyl intermediate, leading to vinyltetrahydrofurans with enantiomeric ratios up to 91.5:8.5.

Selective catalytic hydrogenation of nitriles to primary amines using iron pincer complexes

The selective catalytic hydrogenation of nitriles to primary amines with the well-defined Fe(PNP^Cy) pincer complex 2 is reported.

Efficient Synthesis of Differentiated syn-1,2-Diol Derivatives by Asymmetric Transfer Hydrogenation-Dynamic Kinetic Resolution of α-Alkoxy-Substituted β-Ketoesters

Asymmetric transfer hydrogenation was applied to a wide range of racemic aryl α-alkoxy-β-ketoesters in the presence of well-defined, commercially available, chiral catalyst Ru(II) -(N-p-toluenesulfonyl-1,2-diphenylethylenediamine) and a 5:2 mixture of formic acid and triethylamine as the hydrogen source. Under these conditions, dynamic kinetic resolution was efficiently promoted to provide the corresponding syn α-alkoxy-β-hydroxyesters derived from substituted aromatic and heteroaromatic aldehydes with a high level of diastereoselectivity (diastereomeric ratio (d.r.)>99:1) and an almost perfect enantioselectivity (enantiomeric excess (ee)>99 %). Additionally, after extensive screening of the reaction conditions, the use of Ru(II) - and Rh(III) -tethered precatalysts extended this process to more-challenging substrates that bore alkenyl-, alkynyl-, and alkyl substituents to provide the corresponding syn α-alkoxy-β-hydroxyesters with excellent enantiocontrol (up to 99 % ee) and good to perfect diastereocontrol (d.r.>99:1). Lastly, the synthetic utility of the present protocol was demonstrated by application to the asymmetric synthesis of chiral ester ethyl (2S)-2-ethoxy-3-(4-hydroxyphenyl)-propanoate, which is an important pharmacophore in a number of peroxisome proliferator-activated receptor α/γ dual agonist advanced drug candidates used for the treatment of type-II diabetes.

Highly diastereo- and enantioselective synthesis of monodifferentiated syn-1,2-diol derivatives through asymmetric transfer hydrogenation via dynamic kinetic resolution

The first enantio- and diastereoselective approach to alpha-alkoxy-substituted syn-beta-hydroxyesters through highly efficient catalytic asymmetric transfer hydrogenation via dynamic kinetic resolution reactions from the corresponding racemic beta-ketoesters is described. In this atom-economical process, two contiguous stereogenic centers are generated simultaneously with an excellent diastereoselectivity (up to 99/1) and enantioselectivity (up to 99%), allowing a rapid access to a wide variety of aromatic and heteroaromatic monodifferentiated syn-1,2-diols.

Efficient Synthesis of Novel NK1Receptor Antagonists: Selective 1,4-Addition of Grignard Reagents to 6-Chloronicotinic Acid Derivatives

A new efficient synthesis of two novel classes of NK1 receptor antagonists, among them befetupitant and netupitant, starting from 6-chloronicotinic acid is described. The introduction of the o-tolyl substituent at C4 of the pyridine ring was achieved by a one-pot selective 1,4-Grignard addition/oxidation sequence to 6-chloronicotinic acid or a derivative of it. The scope of this addition/oxidation sequence was examined. It was also shown that the carboxylic function can be converted to a methyl amino group by a Hofmann rearrangement followed by reduction. Furthermore, a new high-yielding synthesis of 2-(3,5-bistrifluoromethylphenyl)-2-methyl propionic acid based on the carbonylation of the tertiary alcohol obtained by Grignard addition of 3,5-bis(trifluoromethyl)bromobenzene to acetone was established.

Piperidine renin inhibitors: from leads to drug candidates

Non-peptidomimetic renin inhibitors of the piperidine type represent a novel structural class of compounds potentially free of the drawbacks seen with peptidomimetic compounds so far. Synthetic optimization in two structural series focusing on improvement of potency, as well as on physicochemical properties and metabolic stability, has led to the identification of two candidate compounds 14 and 23. Both display potent and long-lasting blood pressure lowering effects in conscious sodium-depleted marmoset monkeys and double transgenic rats harboring both the human angiotensinogen and the human renin genes. In addition, 14 normalizes albuminuria and kidney tissue damage in these rats when given over a period of 4 weeks. These data suggest that treatment of chronic renal failure patients with a renin inhibitor might result in a significant improvement of the disease status.

Synthesis of (1S,3aS)-8-(2,3,3a,4,5, 6-hexahydro-1H-phenalen-1-yl)-1-phenyl-1,3,8-triaza-spiro[4. 5]decan-4-one, a potent and selective orphanin FQ (OFQ) receptor agonist with anxiolytic-like properties

The development of 8-(2,3,3a,4,5, 6-hexahydro-1H-phenalen1-yl)-1-phenyl-1,3,8-triaza-spiro[4. 5]decan-4-ones 3 starting from (RS)-8-acenaphten-1-yl-1-phenyl-1,3, 8-triazaspiro[4.5]decan-4-one 1 is reported. The synthesis and the binding affinities at human OFQ and opioid (micro, kappa, delta) receptors of the stereoisomers 3a-f are described. In vitro the most selective compound, (1S,3aS)-8-(2,3,3a,4,5, 6-hexahydro-1H-phenalen1-yl)-1-phenyl-1,3,8-triaza-spiro[4. 5]decan-4-one 3c, was found to act as a full agonist at the OFQ receptor in the GTPgamma(35)S binding test. It turned out to be selective versus a variety of other neurotransmitter systems. When tested in vivo following intraperitoneal injection, compound 3c was found to decrease neophobia in a novel environment and to exhibit dose-dependent anxiolytic-like effects in the elevated plus-maze procedure, thus confirming the effects observed following intracerebroventricular infusion of the OFQ peptide in rat.

Substituted piperidines--highly potent renin inhibitors due to induced fit adaptation of the active site

The identification, synthesis and activity of a novel class of piperidine renin inhibitors is presented. The most active compounds show activities in the picomolar range and are among the most potent renin inhibitors ever identified.