Substituent Effect on the Catalytic Activity of Ruthenium(II) Complexes Bearing a Pyridyl-Supported Pyrazolyl-Imidazolyl Ligand for Transfer Hydrogenation of Ketones

http://pubs.acs.org/doi/10.1021/acs.organomet.5b00727



Substituent Effect on the Catalytic Activity of Ruthenium(II) Complexes Bearing a Pyridyl-Supported Pyrazolyl-Imidazolyl Ligand for Transfer Hydrogenation of Ketones
Huining Chai†, Tingting Liu†, Qingfu Wang†, and Zhengkun Yu*†‡

† Dalian Institute of Chemical Physics, Chinese Academy of Sciences, 457 Zhongshan Road, Dalian, Liaoning 116023, People’s Republic of China
‡ State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 354 Fenglin Road, Shanghai 200032, People’s Republic of China
Organometallics, Article ASAP
DOI: 10.1021/acs.organomet.5b00727
Publication Date (Web): October 20, 2015





Air- and moisture-stable ruthenium(II) complexes bearing a multisubstituted pyrazolyl-imidazolyl-pyridine ligand were synthesized and structurally characterized by NMR and X-ray single-crystal crystallographic analyses. The substituents on the imidazolyl moiety of the NNN ligand exhibited a remarkable impact on the catalytic activity of the corresponding Ru(II) complexes for transfer hydrogenation of ketones in refluxing 2-propanol, following the order NHTs > Me > H > NO2, to tune the catalytic activity. The highest final TOF value of 345 600 h–1was reached by means of 0.05 mol % of the Ru(II)-NHTs-substituted NNN complex as the catalyst. The corresponding structurally confirmed RuH complexes are proposed as the catalytically active species.

Nickel-catalyzed arylation of heteroaryl-containing diarylmethanes: exceptional reactivity of the Ni(NIXANTPHOS)-based catalyst

http://pubs.rsc.org/en/Content/ArticleLanding/2016/SC/C5SC03704B?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+rss%2FSC+%28RSC+-+Chem.+Sci.+latest+articles%29#!divAbstract


Nickel-catalyzed arylation of heteroaryl-containing diarylmethanes: exceptional reactivity of the Ni(NIXANTPHOS)-based catalyst
Xinyu Cao,ab Sheng-Chun Sha,b Minyan Li,b Byeong-Seon Kim,b Catherine Morgan,b Rudan Huang,a Xiaodong Yangc and Patrick J. Walsh*b

Show Affiliations
Chem. Sci., 2016, Advance Article
DOI: 10.1039/C5SC03704B
Received 30 Sep 2015, Accepted 07 Oct 2015
First published online 26 Oct 2015





Nickel(0)-catalyzed cross-coupling of heteroaryl-containing diarylmethanes with both aryl bromides and chlorides has been achieved. The success of this reaction relies on the introduction of a unique nickel/NIXANTPHOS-based catalyst system, which provides a direct route to triarylmethanes from heteroaryl-containing diarylmethanes. Reactivity studies indicate the Ni(NIXANTPHOS)-based catalyst exhibits enhanced reactivity over XANTPHOS derivatives and other Ni(phosphine)-based catalysts in the reactions examined.

How π back-donation quantitatively controls the CO stretching response in classical and non-classical metal carbonyl complexes

http://pubs.rsc.org/en/Content/ArticleLanding/2015/SC/C5SC02971F?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+rss%2FSC+%28RSC+-+Chem.+Sci.+latest+articles%29#!divAbstract


How π back-donation quantitatively controls the CO stretching response in classical and non-classical metal carbonyl complexes
Giovanni Bistoni, Sergio Rampino, Nicola Scafuri, Gianluca Ciancaleoni, Daniele Zuccaccia, Leonardo Belpassi and Francesco Tarantelli

Chem. Sci., 2015, Accepted Manuscript
DOI: 10.1039/C5SC02971F
Received 11 Aug 2015, Accepted 23 Oct 2015
First published online 26 Oct 2015

The CO stretching response upon coordination to a metal M to form [(L)nM(CO)]m complexes (L is an auxiliary ligand) is investigated in relation to the σ donation and π back-donation components of the M–CO bond and to the electrostatic effect exerted by the ligand-metal fragment. Our analysis encompasses over 30 carbonyls, in which the relative importance of donation, back-donation and electrostatics are varied either through the ligand, in a series of [(L)Au(CO)]0/+gold(I) complexes, or through the metal in a series of anionic, neutral and cationic homoleptic carbonyls. Charge-displacement analysis is used to obtain well-defined, consistent measures of σ donation and π back-donation charges, as well as of the σ and π components of CO polarization. It is found that all complexes feature a comparable charge flow of σ symmetry (both in the M–CO bonding region and in the CO fragment itself), which is therefore largely uncorrelated to CO response. By contrast, π back-donation is exceptionally variable and is found to correlate tightly with the change in CO bond distance, with the shift in CO stretching frequency, and with the extent and direction (C→O or C←O) of the CO π polarization. As a result, we conclusively show that π back-donation can be an important bond component also in "non-classical" carbonyls and we actually provide the framework in which the spectrosopic data on coordinated CO can be used to extract quantitative information on the π donor properties of metal-ligand moieties.

Chemoselective Palladium-Catalyzed Deprotonative Arylation/[1,2]-Wittig Rearrangement of Pyridylmethyl Ethers

http://pubs.rsc.org/en/Content/ArticleLanding/2015/SC/C5SC02739J?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+rss%2FSC+%28RSC+-+Chem.+Sci.+latest+articles%29#!divAbstract


Chemoselective Palladium-Catalyzed Deprotonative Arylation/[1,2]-Wittig Rearrangement of Pyridylmethyl Ethers
Feng Gao, Byeong-Seon Kim and Patrick Walsh

Chem. Sci., 2015, Accepted Manuscript
DOI: 10.1039/C5SC02739J
Received 27 Jul 2015, Accepted 26 Oct 2015
First published online 27 Oct 2015


Control of chemoselectivity is one of the most challenging problems facing chemists and is particularly important in the synthesis of bioactive compounds and medications. Herein, the first highly chemoselective tandem C(sp3)–H arylation/[1,2]-Wittig rearrangement of pyridylmethyl ethers is presented. The efficient and operationally simple protocols enable generation of either arylation products or tandem arylation/[1,2]-Wittig rearrangement products with remarkable selectivity and good to excellent yields (60−99%). Choice of base, solvent, and reaction temperature play a pivotal role in tuning the reactivity of intermediates and controlling the relative rates of competing processes. The novel arylation step is catalyzed by a Pd(OAc)2/NIXANTPHOS-based system via a deprotonative cross-coupling process. The method provides rapid access to skeletally diverse aryl(pyridyl)methanol core structures, which are central components of several medications.

Hydrolysis of woody biomass by a biomass-derived reusable heterogeneous catalyst

http://pubs.rsc.org/en/Content/ArticleLanding/2016/SC/C5SC03377B?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+rss%2FSC+%28RSC+-+Chem.+Sci.+latest+articles%29#!divAbstract


Hydrolysis of woody biomass by a biomass-derived reusable heterogeneous catalyst
Hirokazu Kobayashi,ab Hiroyuki Kaiki,ab Abhijit Shrotri,a Kota Techikawaraab and Atsushi Fukuoka*ab

Show Affiliations
Chem. Sci., 2016, Advance Article
DOI: 10.1039/C5SC03377B
Received 08 Sep 2015, Accepted 14 Oct 2015
First published online 15 Oct 2015








Biomass is the sole carbon-based renewable resource for sustaining the chemical and fuel demands of our future. Lignocellulose, the primary constituent of terrestrial plants, is the most abundant non-food biomass, and its utilisation is a grand challenge in biorefineries. Here we report the first reusable and cost-effective heterogeneous catalyst for the depolymerisation of lignocellulose. Air oxidation of woody biomass (Eucalyptus) provides a carbonaceous material bearing an aromatic skeleton with carboxylic groups (2.1 mmol g−1) and aliphatic moieties. This catalyst hydrolyses woody biomass (Eucalyptus) to sugars in high yields within 1 h in trace HCl aq. Furthermore, after the reaction, the solid residue composed of the catalyst and insoluble ingredients of woody biomass is easily transformed back to fresh catalyst by the same air oxidation method. This is a self-contained system using woody biomass as both the catalyst source and substrate for realising facile catalyst preparation and recycling.

Water opens the door to organolithiums and Grignard reagents: exploring and comparing the reactivity of highly polar organometallic compounds in unconventional reaction media towards the synthesis of tetrahydrofurans

http://pubs.rsc.org/en/Content/ArticleLanding/2015/SC/C5SC03436A?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+rss%2FSC+%28RSC+-+Chem.+Sci.+latest+articles%29#!divAbstract




Water opens the door to organolithiums and Grignard reagents: exploring and comparing the reactivity of highly polar organometallic compounds in unconventional reaction media towards the synthesis of tetrahydrofurans
Luciana Cicco, Stefania Sblendorio, Rosmara Mansueto, Filippo Maria Perna, Antonio Salomone, Saverio Florio and Vito Capriati

Chem. Sci., 2015, Accepted Manuscript
DOI: 10.1039/C5SC03436A
Received 11 Sep 2015, Accepted 02 Nov 2015
First published online 03 Nov 2015


It has always been a firm conviction of the scientific community that the employment of both anhydrous conditions and water-free reaction media are required for the successful handling of organometallic compounds with highly polarised metal–carbon bonds. Herein, we describe that, under heterogeneous conditions, Grignard and organolithium reagents can smoothly undergo nucleophilic additions to γ-chloroketones, on the way to 2,2-disubstituted tetrahydrofurans, “on water”, competitively with protonolysis, under batch condition, at room temperature and under air. The reactivity of the above organometallic reagents has also been investigated in anhydrous conventional organic solvents and in bio-based eutectic and low melting mixtures for comparison. The scope and limitations of this kind of reaction are discussed.

Iron-Catalyzed Directed C2-Alkylation and Alkenylation of Indole with Vinylarenes and Alkynes

http://pubs.acs.org/doi/abs/10.1021/ol503395g

Iron-Catalyzed Directed C2-Alkylation and Alkenylation of Indole with Vinylarenes and Alkynes

Mun Yee Wong, Takeshi Yamakawa, and Naohiko Yoshikai*

Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological Universåity, Singapore 637371, Singapore

Org. Lett., 2015, 17 (3), pp 442–445
DOI: 10.1021/ol503395g
Publication Date (Web): January 9, 2015

Abstract

An iron–N-heterocyclic carbene catalyst generated from an iron(III) salt, an imidazolinium salt, and a Grignard reagent promotes alkylation and alkenylation reactions at the indole C2-position with vinylarenes and internal alkynes, respectively, via imine-directed C–H activation. The former reaction affords 1,1-diarylalkane derivatives with exclusive regioselectivity. Deuterium-labeling experiments suggest that these reactions involve oxidative addition of the C–H bond to the iron center, insertion of the unsaturated bond into the Fe–H bond, and C–C reductive elimination.