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International audience; α-carbonyl homoallylic alcohols have been synthesized in a one-pot reaction from benzaldehyde and allylic alcohols. The nickel-catalyzed allylation of α-hydroxyketones has first been studied and allowed the identification of Ni(cod)2/dppf as the most suitable catalytic system. The tandem reaction that combines the benzoin condensation of aldehydes (synthesis of α-hydroxyketones) promoted by the 1,3-dimethylimidazolium chloride/DBU system and the nickel-catalyzed allylic alkylation with allylic alcohol has been realized in EtOH as green solvent. The reaction is 100 % atom-economical and water is formed as sole by-product. A broad scope of different benzaldehyde derivatives as well as various allylic alcohols is also described.

The reaction of a nickel precursor with an enanti­omerically pure amino-oxime issued from (R)-limonene led to the formation of bis­[κ3 N,N,N-(amino­oxime)-μ-chlorido]­dichloro­dinickel as a new dinuclear nickel complex., A dinuclear nickel complex with (S)-limonene based amino­oxime ligand has been isolated and its crystal structure determined. The resolved structure of dichloridobis­{(2S,5R)-2-methyl-5-(prop-1-en-2-yl)-2-[(pyridin-2-yl)methyl­amino]­cyclo­hexan-1-one oxime}dinickel(II), [Ni2Cl2(C16H23ClN3O)2], at 100 K has monoclinic (P21) symmetry. The two NiII ions in the dinuclear complex are each coordinated in a distorted octa­hedral environment by three nitro­gen atoms, a terminal chloride and two μ bridging chlorides. Each oxime ligand is coordinated to nickel(II) by the three nitro­gen atoms, leading to two five-membered chelate rings, each displaying an envelope conformation. In the crystal, numerous inter­molecular and intra­molecular hydrogen bonds lead to the formation of a three-dimensional network structure.

The enantioselective hydroalkoxylation of butadiene with ethanol has been performed in the presence of nickel-based catalysts and chiral diphosphine ligands. Ee’s up to 77% could be obtained from the use of atropoisomeric chiral ligands such as Segphos. The kinetics parameters of the reaction were determined using a qualitative kinetic model to better explain the l/b isomerization and racemization processes observed for long reaction times.

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The [Ni(COD)2]/P P-catalysed hydroalkoxylation of butadiene to form butenyl ethers is studied mechanistically, where P P = 1,4-bis(diphenylphosphino)butane (dppb) and 1,2-bis(diphenylphosphinomethyl)benzene (dppmb). Experimental studies suggest the intermediacy of [(P P)Ni(0)(butadiene)] and [(P P)Ni(II)(allyl)] intermediates and rule out the involvement of Ni-H species. The related species [(dppb)Ni(1,4-diphenylbutadiene)], 1, and [(P P)Ni(crotyl)(Cl)] complexes 2 (P P = dppmb) and 3 (P P = dppb) have been synthesized and characterized on the basis of VT NMR spectroscopy and X-ray crystallographic studies. 2 and 3 are shown to be catalytically competent for the hydroalkoxylation reaction. Computational studies on [(dppmb)Ni(butadiene)] indicate a facile protonation that form a cationic allylic intermediate [(dppmb)Ni(-C4H7)]OMe. C-O bond formation then occurs via external attack by the solvent-stabilized methoxide nucleophile. Hydroalkoxylation proceeds with modest computed barriers of ca. 15 ...

Isosorbide is a diol derived from sorbitol and obtained through dehydration reactions that has raised much interest in the literature over the past few decades. Thus, this platform chemical is a biobased alternative to a number of petrosourced molecules that can find applications in a large number of technical specialty fields, such as plasticizers, monomers, solvents or pharmaceuticals. The synthesis of isosorbide is still a technical challenge, as several competitive reactions must be simultaneously handled to promote a high molar yield and avoid side reactions, like degradation and polymerization. In this purpose, many studies have proposed innovative and varied methods with promising results. This review gives an overview of the synthesis strategies and catalysts developed to access this very attractive molecule, pointing out both the results obtained and the remaining issues connected to isosorbide synthesis.

The palladium catalyzed carboxytelomerization reaction of alcohols with butadiene allows for efficient and atom-economical access to unsaturated alkyl nona-3,8-dienoate esters. The study focused on the nature of the catalyst (phosphine and acid) with ethanol. Commercially available triarylphosphines and carboxylic acids associated with a simple palladium precursor appear to be the best combination for in situ generation of the catalyst. The reaction conditions were further optimized and the carboxytelomerization reaction was efficiently applied to the full transformation of several industrially relevant agro-based monoalcohols and polyols.

International audience; Homogeneous catalytic dehydration of sorbitol to isosorbide has been performed with a series of metal tosylates as catalysts. Conversions up to 100 % and selectivities into isosorbide up to 67% were obtained with Bi(OTs)3. The metals were exchanged with acidic sites of sulfonic resins and the resulting materials were evaluated as heterogeneous catalysts. On the contrary to their homogeneous counter parts, the heterogenized metal sites are non-active. The catalytic activity of the modified resins was systematically diminished in comparison to the native resins. The inhibition is greatly dependent on the nature of the metal and, on a larger extent, of the used resin for the cation exchange.

The palladium catalyzed telomerization of butadiene with glycerol has been efficiently performed with bubbling butadiene at atmospheric pressure leading to high selectivities into monooctadienyl glycerylethers. The catalytic activity is found to be stable for a long period of time, up to 5 days, giving rise to turnover numbers as high as 1000. The reaction has been extended to isosorbide and solketal with always selective production of the monotelomers over long time.

Hydroalkoxylation of butadiene has been performed in the presence of nickel precatalysts associated with chelating diphosphine ligands. High butadiene conversions and selectivities forming alkyl butenyl ethers were obtained with low catalyst loading. Reactions were performed with a wide scope of primary alcohols including benzylic alcohol derivatives and bio-sourced alcohols. In the same way, the scope of dienes that can be reacted according to this reaction has been also studied. Substituted butadiene derivatives have shown a lower reactivity compared to butadiene. Isoprene formed OC5 alkenyl ethers with a high regioselectivity for one branched isomeric form.

International audience; The catalytic hydroalkoxylation of butadiene with glycerol has been performed for the first time thanks to the use of nickel catalysts and an appropriate solvent. Optimization of the reaction conditions allowed obtaining 100% glycerol conversion into a mixture of glyceryl mono- and dibutenyl ethers. The experimental protocols used involved batch experiments or continuous feeding of butadiene at atmospheric pressure. The reaction has then been scaled up to produce multigrams of each pure monoethers and diethers according to simple decantation/distillation procedures. The ethers were further hydrogenated to their corresponding alkyl glyceryl ethers.

The hydrogenation of N-unsubstituted cyclic imides to the corresponding cyclic amines has been performed selectively with heterogeneous catalysts obtained from rhodium and molybdenum carbonyl precursors. Various substrates were reduced in good to high yields and selectivities. Platinum-based catalysts also proved to be efficient. Furthermore, gram-scale experiments were performed and the catalysts could be recycled.

A chiral ( R ) key intermediate of the biologically active form of terutroban has been prepared by asymmetric hydrogenation. The catalysts are based on very easily accessible ruthenium complexes modified by chiral phosphorous ligands. The use of the chiral catASium ® T ligands family allowed us to realize this transformation efficiently in terms of yield and enantioselectivity (ee up to 92%) with high substrate/catalyst ratios.

The asymmetric hydrogenation of a series of quinolines substituted by a variety of functionalized groups linked to the C2 carbon atom is providing access to optically enriched 2-functionalized 1,2,3,4-tetrahydroquinolines in the presence of in situ generated catalysts from [Ir(cod)Cl]2, a bisphosphine, and iodine. The enantioselectivity levels were as high as 96% ee.

For the first time, the asymmetric hydrogenation of quinoxaline-2-carboxylates was performed successfully. The best catalysts are based on iridium complexes modified by chiral phosphorous ligands. Accelerated examination of ligands and catalysts has been undertaken by using a Chemspeed workstation, which enables carrying out, in parallel, eight independent catalytic reactions at the laboratory scale. Tetrahydroquinoxaline-2-carboxylates could be obtained with high yields and up to 74% ee.

Glycerol carbonate, straightforwardly issued from glycerol, is functionalized by telomerization with 1,3-butadiene by means of a palladium catalyst, to selectively afford the linear octadienylglyceryl carbonate. Further hydrogenation of the double bonds gives the saturated functionalized product. The resulting glyceryl carbonate ethers are tentatively co-polymerized with lactones in the presence of a neodymium initiator. Copolymers with up to ca 4 mol % of inserted carbonate are received. The rather low amount of inserted co-monomer is found sufficient to modulate the thermal behavior of polycaprolactone.

For the first time, the asymmetric hydrogenation of quinoxaline-2-carboxylates was performed successfully. The best catalysts are based on iridium complexes modified by chiral phosphorous ligands. Accelerated examination of ligands and catalysts has been undertaken by using a Chemspeed workstation, which enables carrying out, in parallel, eight independent catalytic reactions at the laboratory scale. Tetrahydroquinoxaline-2-carboxylates could be obtained with high yields and up to 74% ee.

The asymmetric hydrogenation of a new series of 2-functionalized quinolines has been developed in the presence of in situ generated catalysts obtained from [Ir(cod)Cl]2/(R)-bisphosphine/I2 combinations. The enantioselectivity levels were as high as 84–94% ee for the synthesis of 1,2,3,4-tetrahydroquinolines.

A new family of bifunctional, optically pure α-amino-oxime ligands based on (R)-limonene has been synthesized and used as chiral inducers for enantioselective hydrogen transfer reactions on various ketones in the presence of ruthenium catalysts. The X-ray structures of Ru―amino-oxime complexes are also described. Chirality 24:675–682, 2012. © 2012 Wiley Periodicals, Inc.

The telomerization of butadiene with solketal (1,2-isopropylideneglycerol) in the presence of palladium complexes has been studied under aqueous biphasic conditions. This reaction followed by depro...

The enantioselective hydrogenation of indole esters has been carried out efficiently in the presence of a rhodium catalyst modified by Walphos-type chiral ligands. The addition of a base can be beneficial in some catalytic conditions.

The palladium-catalyzed telomerisation of butadiene with glycerol has been studied under aqueous biphasic conditions both in the presence of a liquid phase of butadiene and under gaseous atmosphere of butadiene. In this last case, gaseous butadiene was continuously added during the whole reaction time keeping constant its pressure. Most of the products formed have been fully characterized. The influence of various experimental parameters has been checked with the aim to obtain high activities and selectivities either into mono-, di- or tritelomers.

N-Methylimidazole was used to promote the acylation of secondary racemic alcohols and to carry out their kinetic resolution through intermediate chiral acyl imidazolium chlorides. The kinetic resolution could be turned into a catalytic process in the presence of a catalytic amount of N-methylimidazole.

Enantiopure β-aminoalcohol ligands based on α-pinene have been synthesized in a few steps and used in asymmetric transfer hydrogenation of acetophenone catalyzed by ruthenium complexes. High conversions and moderate ee's (up to 45%) have been obtained.

Three co-crystals of tetrabutylammonium and 1-alkyl-3-methylimidazolium bistrifluoromethanesulfonate, where alkyl are: ethyl (co-crystal I ), butyl (co-crystal II ) or (±)-2-methylbutyl (co-crystal III ) have been crystallized by slow evaporation of a chloroform solution. The X-rays diffraction studies on single co-crystals revealed that the three crystalline materials obtained are respectively triclinic ( P 1 ¯ ) for I , monoclinic ( P 2 1 / c ) for II and triclinic ( P 1 ¯ ) for III . In each structure, the tetrabutylammonium cations are included in the H-bonds network that link all the imidazolium cations and trifluoromethanesulfonate anions. The H-bonds occur between the acidic protons of the imidazolium ring and the oxygen atoms of the counter ion. No supramolecular interaction (except obviously electrostatic) is observed between the tetrabutylammonium cations and the trifluoromethanesulfonate anions.

International audience; Cationic iridium complexes based on enantiomerically pure tetrathiafulvalene-oxazoline ligands have been used in the asymmetric hydrogenation of N-(phenylethylidene)aniline. Complete conversions with ee's up to 68% could be reached in the case of the TTF-phosphinooxazoline (TTF-PHOX) ligands.

The preparation of optically pure secondary alcohols in the presence of catalysts based on chiral ligands derived from monoterpenes, such as pinenes, limonenes and carenes, is reviewed. A wide variety of these ligands has been synthesized and used in several catalytic reactions, including hydrogen transfer, C-C bond formation via addition of organozinc compounds to aldehydes, hydrosilylation, and oxazaborolidine reduction, leading to high activities and enantioselectivities.

The hydrogenation of N-unsubstituted cyclic imides to the corresponding cyclic amines has been performed selectively with heterogeneous catalysts obtained from rhodium and molybdenum carbonyl precursors. Various substrates were reduced in good to high yields and selectivities. Platinum-based catalysts also proved to be efficient. Furthermore, gram-scale experiments were performed and the catalysts could be recycled.

The preparation of optically pure secondary alcohols in the presence of catalysts based on chiral ligands derived from monoterpenes, such as pinenes, limonenes and carenes, is reviewed. A wide variety of these ligands has been synthesized and used in several catalytic reactions, including hydrogen transfer, C-C bond formation via addition of organozinc compounds to aldehydes, hydrosilylation, and oxazaborolidine reduction, leading to high activities and enantioselectivities.

Rh-, Co- or Ir-promoted cyclization of 1,6-enynes in the presence of a hydrosilane and carbon monoxide leads to the selective formation of functionalized cyclic compounds. Various chiral phosphine type ligands have been used in order to obtain enantiomerically enriched carbocycles. The asymmetric process proceeded with modest enantioselectivities.

Recent advances in the synthesis and coordination chemistry of aminophosphine phosphinite ligands (AMPP) and closely related auxiliaries are reviewed. Asymmetric catalytic reactions involving various organometallic AMPP complexes are presented.

The asymmetric hydrogenation of a series of quinolines substituted by a variety of functionalized groups linked to the C2 carbon atom is providing access to optically enriched 2-functionalized 1,2,3,4-tetrahydroquinolines in the presence of in situ generated catalysts from [Ir(cod)Cl]2, a bisphosphine, and iodine. The enantioselectivity levels were as high as 96% ee.

The synthesis of ethers derived carbohydrates/polyols used as intermediates in multistep synthesis or large scale commodity products such as detergents is since a long time an issue of concern for organic chemists. The conventional Williamson reaction is the most used synthetic method to build an ether function from a free hydroxyl group. Very selective transformations that use this procedure have been achieved and progresses based on this reaction are always of actuality. Alternatively to the Williamson reaction, catalytic approaches aiming at opening salt free accesses to ethers have more recently emerged. This evolution is pushed by the growing interest dedicated to greener synthetic approaches that find a particular echo in the field of carbohydrates chemistry. This chapter sets up a panorama of the methods used to access ethers derived from the free hydroxyl groups of carbohydrates/polyols. This overview of course includes the stoichiometric Williamson reaction, largely and even, in some cases, routinely employed at the laboratory and industrial scales. A particular attention is given to the recent developments in protecting groups for multistep synthesis and the large scale production of alkylcelluloses. New approaches based on the use of homogeneous or heterogeneous catalysis have more recently emerged and now offer a new panel of reactions to build ether functions. Several examples of salt free acid or metal catalyzed reactions transformations are depicted, thus showing progresses that have been and remain to be done in this field.

New chiral unsymmetrical ligands containing deficient phosphorous moieties based on (S)-prolinol and (S)-oxoprolinol have been synthesised and used as chiral auxiliaries for the platinum- and rhodium-catalysed enantioselective hydroformylations of styrene. The new ligands are obtained readily by reaction of the amino alcohols with a chlorophosphonite. The beneficial effect induced by the electron-deficient phosphorous ends provided the branched aldehyde in up to 44% ee. A crystal structure of the platinum complex 5 is described.

Enantiopure P-chiral β-aminophosphine oxides and the corresponding β-aminophosphines have been synthesised and used as chiral auxiliaries in ruthenium catalysed asymmetric transfer hydrogenation of arylketones producing optically active alcohols up to 80% ee. Both types of auxiliaries provide comparable induction levels but the β-aminophosphine oxide ligands induce higher catalytic activities generally. In some experiments, when changing the achiral arene ligand in the catalyst precursor, a peculiar reversal of the product configuration was observed.

We have developed a new class of electron-deficient aminophosphonite–phosphite ligands based on (1 R ,2 S )-ephedrine and chlorophosphites. These ligands were tested in rhodium catalysed hydroformylation of styrene and led to reactions with high regio and chemoselectivities into the branched aldehyde but nevertheless with low enantioselectivities.

We have developed new electron rich chiral bisphosphinites from mannitol. The new ligands have been found to be efficient chiral auxiliaries for rhodium catalyzed hydrogenation of functionalized ketones leading to hydroxy compounds in up to 86% ee.

Enantiopure β-aminophosphine oxide ligands have been synthesized and used in asymmetric transfer hydrogenation of ketones. Optically active alcohols are obtained in high yields and with up to 84% enantiomeric excess.

Biphasic hydroformylation of dec-1-ene and styrene, at commercially competitive rates, can be successfully performed in imidazolium triflate ionic liquids; the ionic liquid network forms 'inclusion complexes' with the phosphane ligands used to modify the rhodium catalyst.

The synthesis and coordination chemistry of aminophosphine-phosphinites (AMPP) and closely related ligands is reviewed. Asymmetric catalytic reactions involving organometallic-AMPP complexes are presented. Examples of enantioselective C–C bond formation in the presence of nickel- (dienes and diene-olefins dimerization, allylic substitution) and palladium-AMPP catalysts (nucleophilic addition to allylic substrates), hydroformylation based on platinum and rhodium complexes, rhodium-based hydrosilylation, hydrogenation of CC and CO bonds in the presence of rhodium and ruthenium complexes and homo Diels-Alder catalyzed by cobalt species are presented.

Sucrose-butadiene telomerization is efficiently carried out in water or water-organic medium in the presence of a palladium salt and TPPTS (TPPTS = trisodium tris(m-sulfonatophenyl)phosphine as catalyst. Mono- and dioctadienylether compounds are selectively obtained using a NaOH 1 M/isopropanol mixture.

The synthesis of new homochiral bis(aminophosphanes) (BAMP) 1–5 and their application in rhodium based asymmetric hydrogenation of dihydro-4,4-dimethyl-2,3-furandione 12 and N -benzylbenzoylformamide 14 are presented. Under mild conditions, the hydrogenations led to high enantiomeric excesses (up to 87% and 75% ee respectively for both substrates).