Biphasic Palladium-Catalyzed Hydroesterification in a Polyol Phase: Selective Synthesis of Derived Monoesters.

The palladium-catalyzed hydroesterification reaction was performed with polyols and olefins in a liquid/liquid biphasic system composed of unreacted polyol on the one hand and apolar reaction products/organic solvents on the other hand. The palladium-based catalyst was immobilized in the polyol phase thanks to the use of cationic triarylphosphines possessing pendent protonated amino groups in the acidic reaction medium or to the sulfonated phosphine TPPTS (trisodium triphenylphosphine-3,3',3''-trisulfonate). Owing to the insolubility of the products in the catalytic phase, this approach allowed the synthesis of monoesters of polyols with high selectivities as well as the easy separation of the catalyst through simple decantation.

Cross-metathesis of biosourced fatty acid derivatives: a step further toward improved reactivity.

The improved catalytic conversion of bioresources, namely unsaturated fatty acid derivatives, is presented. The targeted reaction is ruthenium-catalyzed cross-metathesis with functionalized olefins (α,β-unsaturated esters), that affords shorter diesters. These can be used as biosourced (pre)monomers for the production of polyesters.

Chiral ligands derived from monoterpenes: application in the synthesis of optically pure secondary alcohols via asymmetric catalysis.

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.

Synthesis of 1,4:3,6-dianhydrohexitols diesters from the palladium-catalyzed hydroesterification reaction.

The hydroesterification of alpha olefins has been used to synthesize diesters from bio-based secondary diols: isosorbide, isomannide, and isoidide. The reaction was promoted by 0.2% palladium catalyst generated in situ from palladium acetate/triphenylphosphine/para-toluene sulfonic acid.

Isoprene-styrene chain shuttling copolymerization mediated by a lanthanide half-sandwich complex and a lanthanidocene: straightforward access to a new type of thermoplastic elastomers.

A lanthanide half-sandwich complex and a ansa lanthanidocene have been assessed for isoprene-styrene chain shuttling copolymerization with n-butylethylmagnesium (BEM). In the presence of 1 equiv BEM, a fully amorphous multiblock microstructure of soft and hard segments is achieved. The microstructure consists of poly(isoprene-co-styrene) blocks, with hard blocks rich in styrene and soft blocks rich in isoprene.

Nickel-catalysed hydroalkoxylation reaction of 1,3-butadiene: ligand controlled selectivity for the efficient and atom-economical synthesis of alkylbutenyl ethers.

The nickel-catalysed hydroalkoxylation of butadiene is promoted by a nickel(0)/dppb catalyst (dppb = 1,4-bis(diphenylphosphino)butane; see scheme). By following this new synthetic procedure, alkylbutenyl ethers are readily obtained from an alcohol and 1,3-butadiene with exclusion of dimerisation and telomerisation products.

Synthesis of α-alkylated β-ketoesters by alkoxycarbonylation/Michael addition domino reaction.

The palladium-catalyzed alkoxycarbonylation of an α-chloro ketone can be efficiently combined to a Michael addition reaction in a new two-step domino reaction, allowing the synthesis of original highly functionalized α-alkylated β-ketoesters. The scope of the reaction was extended to several α-chloro ketones and Michael acceptors with moderate to very good yields.

α-Amino-oximes based on optically pure limonene: a new ligands family for ruthenium-catalyzed asymmetric transfer hydrogenation.

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.

17O NMR gives unprecedented insights into the structure of supported catalysts and their interaction with the silica carrier.

Flame silica was surface-labeled with (17)O, through isotopic enrichment of both siloxanes and silanols. After heat treatment at 200 and 700 °C under vacuum, the resulting partially dehydroxylated silica materials were investigated by high-field solid-state (1)H and (17)O NMR. More specifically, MQ MAS and HMQC sequences were used to probe the (17)O local environment.

Pd-catalyzed domino carbonylative-decarboxylative allylation: an easy and selective monoallylation of ketones.

In the presence of an allyl alcohol, α-chloroacetophenones undergo an allyloxycarbonylation reaction followed by in situ decarboxylative allylation to selectively afford the corresponding monoallylated ketones via a Pd-catalyzed domino sequence. The scope of the reaction was extended to substituted α-chloroacetophenones as well as various allyl alcohols.

Effect of chain unsaturation on the self-association of tri- and tetraethylene glycol octyl ethers obtained by butadiene telomerization.

2,7-Octadienyl ethers of tri- and tetraethylene glycol (C(8:2)E(3) and C(8:2)E(4)) have been synthesized by the atom-economical butadiene telomerization of the corresponding poly(ethylene glycols). On one hand, this synthetic path is attractive because it is expeditious and environmentally benign, and on the other hand, it provides unconventional amphiphiles for which the lipophilic chains possess two double bonds. These two unsaturations increase the global hydrophilicity of the compound, which is also highlighted by the modelization of the compounds using the conductor-like screening model for real solvents (COSMO-RS).

Telomerisation of 1,3-butadiene with 1,4:3,6-dianhydrohexitols: an atom-economic and selective synthesis of amphiphilic monoethers from agro-based diols.

The telomerisation of 1,3-butadiene with a Pd/TPPTS catalytic system in water or an organic solvent was used for the synthesis of C8 ethers from isosorbide, an agro-based diol. The use of water/oil biphasic reaction conditions allowed the selective synthesis of monoethers with improved rates upon using inorganic bases as promotors. As isosorbide is a non-symmetric diol, the two hydroxyl groups display different reactivities.

Unprecedented dual behaviour of a half-sandwich scandium-based initiator for both highly selective isoprene and styrene polymerisation.

Highly cis-1,4 polymerisation of isoprene and syndiospecific polymerisation of styrene were conducted using the same borohydrido half-sandwich scandium pre-initiator.

Cationic borohydrido-neodymium complex: synthesis, characterization and its application as an efficient pre-catalyst for isoprene polymerisation.

The cationic borohydrido lanthanide complex [Nd(BH4)2(THF)5][B(C6F5)4]1, prepared from the reaction of Nd(BH4)3(THF)3 with [HNMe2Phl[B(C6F5)4], is highly active towards isoprene polymerisation upon activation with Al(i-Bu)3, whereas the in situ prepared ternary catalytic combination Nd(BH4)3(THF)3/[HNMe2Ph][B(C6F5)4]/Al(i-Bu)3, albeit less active, displays higher cis-selectivity and better control in terms of macromolecular data.

A well-defined silica-supported dinuclear tungsten(III) amido species: synthesis, characterization and reactivity.

Grafting of [W(2)(NMe(2))(6)] onto dehydroxylated silica affords the well-defined surface species [([triple bond, length as m-dash]Si-O)W(2)(NMe(2))(5)], characterized by elemental analysis, and infrared, Raman and NMR spectroscopies, and the catalytic reactivity of this supported tungsten(III) d(3)-d(3) dimer and of its alkoxide derivatives towards alkynes has been probed.

Well-defined silica-supported rare-earth silylamides.

Rare-earth silylamides [Ln{N(SiMe3)2}3] [1a-d, Ln = Y (1a), La (1b), Nd (1c), Sm (1d)] react with partially dehydroxylated silica to generate the singly surface-bonded species [(Si-O)Ln{N(SiMe3)2}2] (2a-d). Trimethylsilylation of silanols occurs during the grafting process, affording in fine a hydroxyl-free surface. Contacting these well-defined surface species with excess triphenylphosphine oxide yields [(Si-O)Ln{N(SiMe3)2}2(OPPh3)] surface adducts 3a-d as the major (80%) species, leaving about 20% of unreacted siloxide bisamido species (20%).

Rhodium complexes non-covalently bound to cyclodextrins: novel water-soluble supramolecular catalysts for the biphasic hydroformylation of higher olefins.

A new class of cationic alpha-cyclodextrins bearing 2-hydroxy-3-trimethylammoniopropyl groups has been synthesised. We investigated their efficiency as mass-transfer promoters in a biphasic hydroformylation reaction catalysed by a rhodium trisulfonated triphenylphosphine system. These cationic alpha-cyclodextrins greatly increased the reaction rate, the chemoselectivity, and, surprisingly, the linear-to-branched aldehyde ratio.

Silica-supported lanthanide silylamides for methyl methacrylate polymerisation: controlled grafting induces controlled reactivity.

Lanthanide silylamides were grafted onto non-porous silica dehydroxylated at various temperatures, and the surface species nature and relative distribution were correlated with MMA polymerisation activity and selectivity.

New synthesis of 1,4-diketones via rhodium-catalysed 1,4 carbonylative addition of arylboronic acids to alpha,beta-unsaturated ketones.

The reaction of various arylboronic acids with alpha,beta-unsaturated ketones under CO pressure and in the presence of rhodium catalyst yields 1,4-diketones.

Direct Zn-diamine promoted reduction of C=O and C=N bonds by polymethylhydrosiloxane in methanol.

Ketones and imines are chemoselectively reduced at room temperature in methanol to the corresponding alcohols and amines in high yields in a one-step procedure using polymethylhydrosiloxane (PMHS) and a simple zinc-diamine catalyst.

Neodymium alkoxides: synthesis, characterization and their combinations with dialkylmagnesiums as unique systems for polymerization and block copolymerization of ethylene and methyl methacrylate.

The synthesis and characterization (NMR and X-ray) of a variety of neodymium alkoxides derived from simple and functionalized tertiary monoalcohols, and their application as inorganic precursors in combination with dialkylmagnesium reagents for ethylene and methyl methacrylate (MMA) (co)polymerization have been investigated. Salt metathesis reactions between NdCl(3) and sodium alkoxides in THF led to the formation of trinuclear complexes [Nd(3)(mu(3)-OR)(2)(mu(2)-OR)(3)(OR)(4)(thf)(2)] with R=tBu (1), tAm (2), while aggregate structure [Nd(12)(OtAm)(26)(HOtAm)(2)Cl(11)Na].(OEt(2))(2) (3) was obtained when the synthesis was performed in Et(2)O.