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Amaranth (Amaranthus cruentus) is a possible alternative to high-nutritional-value crops. Amaranth seeds are considered to be one of the few sources of phytosqualene (up to 8%). The use of squalene and its hydrogenated form squalane in skincare formulations has been steadily increasing, and the demand for these compounds is expected to rise continuously. The aim of this study was to investigate the amaranth oilseed as a potential ingredient for cosmetic applications. First, an experimental design and optimization were carried out in order to obtain amaranth oil rich in squalane instead of squalene through catalytic hydrogenation. Under the optimal conditions, the resulting oil was fully hydrogenated, with higher stability, and more suitable for cosmetic uses. Furthermore, the effect of the addition of amaranth oil and squalane on the rheological and sensory characteristics of moisturizing cream formulations was assessed. As expected, higher contents of oil and polyunsaturated fatty acids were obtained by supercritical CO2 extraction, and were used for the next step of the experiment. Optimization of the experimental conditions resulted in fully hydrogenated amaranth oil, with higher stability and rich in squalane. Better quality of moisturizing cream formulations was achieved when W/O formulations were enriched with 2% oil, or by adding 1% oil and 1% squalane. The formulation rich in squalane showed a better overall quality compared to other formulations.

International audience; Chiral amines can be synthesized with high yields and enantioselectivities from abundant organic substrates using transition metal catalytic systems containing most of the time an appropriate chiral bidentate ligand. Reductive amination starts from ketones, hydroamination from alkenes, or alkynes in an inter- or intramolecular mode. In the hydroaminoalkylation reaction, a C–H function in α-position with regard to the nitrogen is activated and forms a new C–C bond. In the hydroaminomethylation, a one-pot carbonylation reaction, the olefin reacts with CO/H2 and amine. Complexes chiral-only-at-metal begin to be efficient to perform the photocatalytic chiral amination under mild conditions. Many recent trends are focused onto first-line transition metals. The major difficulties lie in the synthesis of chiral ligands and the design of a suitable coordination sphere.

Biosourced N-acetamide-based himachalenes were synthesized by Lewis acid catalyzed rearrangement of epoxy-himachalene derived from α-cis- and β-himachalenes, the main component of essential oil of Atlas cedar (Cedrus atlantica). Several new chiral polycyclic N-acetamide compounds were obtained with different selectivities depending on the acid used. Among the Lewis acids used, BF3·OEt2 under catalytic and mild conditions is efficient and selective affording the formation of chiral N-acetamides in good yields. Otherwise, using acetonitrile as solvent and reagent was proved as an efficient tool giving access to new N-acetamide-based himachalenes. A mechanism to explain the formation of the different compounds observed in the reaction mixture has also been proposed.

International audience; The successful rhodium catalysed asymmetric intermolecular hydroaminomethylation (HAM) of alkenes using a single catalyst bearing the (R,R)-QuinoxP* ligand is reported. The HAM of α-alkyl acrylates is revealed to be an efficient tool for the regio- and enantioselective synthesis of γ-amino esters with ees up to 86%. HPNMR experiments provided insights into the reaction mechanism.

A new synthetic alternative to the synthesis of 3-methyl indoles and 3-methyl indoline-2-ols with an excellent atomic economy is presented in this study. It is demonstrated that the intramolecular interrupted hydroaminomethylation (HAM) reaction is a powerful tool for the formation of these compounds, which exhibit wide-ranging biological activity. Several

International audience; A numerical study describes the catalytic conversion of glucose into ethylene glycol (EG) in a semi-batch reactor. This analysis couples a set of power law models (homogeneous reactions) and Langmuir-Hinshelwood-Hougen-Watson (LHHW) equations (hydrogenations). For this purpose, the kinetic parameters of the LHHW expressions are estimated for the reaction conditions. Then, the kinetic model evaluates the influence of the H2 pressure and the catalyst concentrations on the selectivity. The results indicate that the EG yield is increased by setting the temperature and the H2 pressure. In this manner, the process reduces the hexitols and methane production and increases the EG yield. The originality of the work is based on the influence of the H2 pressure and the catalyst concentrations in the model.

International audience; From a mixture of α-, β- and γ-himachalenes extracted from waste wood of Atlas cedar (Cedrus atlantica), cadalene (1,6-dimethyl-4-isopropylnaphthalene) and iso-cadalene (1,6-dimethyl-3-isopropylnaphthalene) were produced in two steps with up to 71% ± 5% yield through the ar-himachalene intermediate using I2 and/or AlCl3 as reagents. The selectivity is shown to sharply depend on the operating conditions: while I2/AlCl3 in dichloromethane promotes the formation of cadalene, the formation of iso-cadalene is favored in the presence of AlCl3 in cyclohexane. The bicyclic aromatic compounds were thus obtained through unique rearrangements involving sequential CC bond cleavage/formation and hydride transfer processes. In the absence of AlCl3 or I2, dihydrocurcumene was also found to be formed with up to 70% selectivity. A tentative mechanism is proposed and discussed.

International audience; In the context of atom economy and low environmental impact, synthesis of amines by an efficient catalytic process is of great importance to produce these building blocks for fine chemical industry. The one-pot hydroaminomethylation of alkenes is a tandem reaction which involves three successive steps under CO/H2 pressure to perform the catalyzed hydroformylation of the alkene into the corresponding aldehyde followed by its condensation with a N–H function and the catalyzed hydrogenation of the imine/enamine intermediate into the corresponding saturated amine. Rhodium and more recently ruthenium complexes have been designed to combine high conversions of the reactants and chemoselectivity in the expected amines with high regioselectivity in either the linear or the branched amine. The coordination sphere of the metal according to the presence of ligands, temperature, CO/H2 partial pressures, and nature of the solvent is essential for complying with these selectivity requirements. The rate of the hydroformylation step needs to be fast with regard to the hydrogenation step. The role of amines in the coordination sphere and water, presumably in the second sphere, on the mechanism requires some more studies. Similarly, the enantioselective synthesis of amine is not yet achieved directly and interrupted processes or use of asymmetric organo-catalyzed reductive amination are efficient synthetic ways for producing chiral amines. The separation of the catalyst from the organic products by biphasic or (semi-) heterogeneized systems and its recycling have been demonstrated in many cases. The present review provides a report of the state of the art in this autotandem hydroaminomethylation catalysis and should open prospects in the design of less expensive and abundant metal complexes for reaching at low cost similar and even superior performances.

International audience; The state of the art on the glycerol carbonate (GC) synthesis has been updated since the last published reviews in 2012, 2013, and 2016. Three types of reactions continue to be studied: glycerolysis of urea, transcarbonation of DMC, DEC, or cyclic carbonates with glycerol and reaction using CO2. Among these different routes, DMC and glycerol were selected as the raw materials for the GC synthesis in this work since the transcarbonation from these green reagents leads to high yields and selectivities, using mild conditions including a less energy consuming GC separation process. Catalytic conditions using Na2CO3 seem to be a good compromise to achieve a high yield of GC, leading to an easier purification step without GC distillation. Mild temperatures for the reaction (73–78°C) as well as a low waste amount confirmed by the E-factor calculation, are in favor of controlled costs. Plasticizing properties of synthesized GC were compared to the behaviors of a commercial plasticizer and natural dialkyl carbonates, for a colorless nail polish formulation. The resulting films subjected to mechanical and thermal stresses (DMA and Persoz pendulum) showed the high plasticizing effect of GC toward nitrocellulose based films, probably due to hydrogen bond interactions between GC and nitrocellulose. The GC efficiency gives the possibility to decrease the content of the plasticizer in the formulation. Glycerol carbonate can be thus considered as a biobased ingredient abiding by the green chemistry concepts, and safe enough to be used in an ecodesigned nail polish formulation.

Background A novel series of 1,2,3-triazole derivatives containing 1,4-benzothiazin-3-one ring (7a–9a, 7b–9b), (10a–12a, 10b–12b) and (13–15) were synthesized by 1,3-dipolar cycloaddition reactions of azides α-d-galactopyranoside azide F, 2,3,4,6-tetra-O-acetyl-(d)-glucopyranosyl azide G and methyl-N-benzoyl-α-azidoglycinate H with compounds 4–6. Findings Initially, the reactions were conducted under thermal conditions in ethanol. The reaction leads, each time, to the formation of two regioisomers: (Schemes 2, 3) with yields of 17 to 21% for 1,5-disubstituted 1,2,3-triazole-regioisomers (7b–12b) and yields ranging from 61 to 65% for the 1,4-disubstituted regioisomers (7a–12a). In order to report an unequivocal synthesis of the 1,4-regioisomers and confirm the structures of the two regioisomers obtained in thermal conditions (Huisgen reactions), the method click chemistry (Copper-Catalyzed Azide-Alkyne Cycloaddition) has been used. Conclusions The newly synthesized compounds using cycloaddition reactions were evaluated in vitro for their antibacterial activities against some Gram positive and Gram negative microbial strains. Among the compounds tested, the compound 8a showed excellent antibacterial activities against PA ATCC and Acin ESBL (MIC = 31.2 μg/ml).

International audience; In this work, three novel long-chain alkyl substituted 1,4-benzothiazine derivatives have been synthesized by alkylation reactions under phase transfer catalysis conditions. The obtained compounds (4, 5 and 6) obtained were characterized using 1H- and 13C- NMR spectroscopy and X-ray. Their molecular and crystal structures have been determined by single-crystal X-ray diffraction techniques. The experimental data, were compared with the predicted ones spectral data were also obtained using density functional theory (DFT) at the B3LYP/6-31G(d,p) level of theory. In addition, the closest contacts between the active atoms of the compounds were identified through Hirshfeld surface analyses. According to Monte Carlo simulations, the new compounds can act as good corrosion inhibitors for iron and as moderate ones for copper and aluminum metals.

International audience; New benzimidazolone derivatives (2–5) were synthesized and characterized using NMR and single crystal X-ray diffraction techniques. Along with the experimental data, the predicted spectral data were also obtained using density functional theory (DFT) at the B3LYP/6-31G(d,p) level of theory. In addition, the closest contacts between the active atoms of the compounds were identified through Hirshfeld surface analyses, molecular docking studies, and DFT calculations. The antibacterial activities of derivatives (2–5) against gram-positive and gram-negative microbial strains, such as Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa were also evaluated, and the results obtained showed the antibacterial activities of derivatives (2–5) using a minimum inhibitory concentration (MIC) assay.

International audience; The hydroaminomethylation (HAM) of estragole, a bio-renewable starting material, with di-n-butylamine was studied for the first time resulting in three novel amines. The process consists of the alkene hydroformylation followed by the in situ reductive amination of primarily formed aldehydes. In order to control chemo- and regioselectivities, three classes of phosphorus(III) compounds were employed as ancillaries for rhodium(I) catalysts: phosphine, phosphites and phospholes. Phosphole-promoted systems have showed the best overall performance, being more selective in the hydrofomylation step than non-promoted or phosphite-promoted systems, as well as more efficient in the reductive amination step than the standard triphenylphosphine based system. It has been found that both the double bond isomerization (a concurrent reaction) and the enamine hydrogenation (the last step in the HAM process) are favored by less electron-donating ligands, with phospholes presenting an excellent compromise to ensure high chemoselectivity and reasonably fast formation of target amines.

International audience; An efficient method to obtain chiral 1,2-disubstituted ferrocenyl ligands has been developed. The introduction of planar chirality was accomplished by using 2-thiazoline as an ortho-directing lithiation group, and moreover, these kinds of ligands possess a central chirality from the amino alcohol used in their synthesis. The X-ray analysis and DFT calculations confirmed the diastereoselectivity of ortho-lithiation and the configuration of the planar chirality. The ability of these new bidentate [N,S]-ferrocene ligands to act in Pd-catalyzed asymmetric allylic alkylation has also been demonstrated and compared with their oxazoline counterparts.

International audience; Using the unsymmetrical P–P′ phospholyl(phosphino)methane ligand, complex cis-[RuCl2(κ2-P–P′)2] is easily prepared from [RuCl2(DMSO)4]. The two phosphole-phosphorus atoms lie in the trans position to the two cis-chloro ligands. This complex slowly isomerizes spontaneously at 20 °C to the trans-[RuCl2(κ2-P–P′)2] diastereoisomer where the two phosphole moieties are mutually trans, as well as the two chloro ligands and the two Ph2P moieties. DFT calculations show that this non-classical cis–trans isomerisation process requires a 3 kcal mol−1 energy and involves the decoordination of a phosphole arm.

International audience; We herein report the synthesis and catalytic application of a new family of [N\P], ligands based on the pyrrole ring with alpha-phosphine or phosphole units. Their palladium complexes (3a-d) were obtained in very good yields and their catalytic properties were evaluated in the direct intramolecular arylation to obtain both benzopyranones and phenanthridinones. The air stable complex 3a exhibited the best catalytic performance of this series of complexes, using 1 mol% of catalyst in combination with microwaves to promote this reaction.

International audience; This review presents the recent advances in the rhodium-catalyzed tandem carbonylation reactions involving in the main step the hydroformylation. Such reactions open huge opportunities in synthetic chemistry, since they offer a general efficient strategy to synthesize building blocks for fine chemistry, starting from abundant and low price substrates and avoiding the formation of substantial amounts of by-products. This atom-efficient tandem reaction approach shows that rhodium has a privileged place in the CO chemistry, not only to perform the hydroformylation reaction but also to functionalize the aldehyde function in a one-pot process.

International audience; The reactivity of [Rh(CO)2{(R,R )‐PhBPE}]BF4 (2 ) toward amine, CO and/or H2 was examined by high‐pressure NMR and IR spectroscopy. The two cationic pentacoordinated species [Rh(CO)3{(R,R )‐PhBPE}]BF4 (4 ) and [Rh(CO)2(NHC5H10){(R,R )‐Ph‐BPE}]BF4 (8 ) were identified. The transformation of 2 into the neutral complex [RhH(CO)2{(R,R )‐PhBPE}] (3 ) under hydroaminomethylation conditions (CO/H2, amine) was investigated. The full mechanisms related to the formation of 3 , 4 and 8 starting from 2 are supported by DFT calculations. In particular, the pathway from 2 to 3 revealed the deprotonation by the amine of the dihydride species [Rh(H)2(CO)2{(R,R )‐PhBPE}]BF4 (6 ), resulting from the oxidative addition of H2 on 2 .

The synthesis of the phospholyl(phosphinoborane)methane air- and moisture-stable hybrid ligands 4a–f, starting from 1-phenylphospholes 1a–d, was performed via P–C bond coupling on the methano bridge. Two strategies were investigated, according to the phospholyl moiety used as a nucleophilic or an electrophilic reagent. In the first pathway, the phospholyl anions react with the easily available (chloromethyl)diphenylphosphine–borane 3 to afford ligands 4a–d in 29–67% isolated yields. In the second pathway, the phospholyl(dicyclohexylphosphinoborane)methane ligands 4e,f were synthesized in 18–23% yields, through a nucleophilic substitution on the cyanophosphole. Removal of the BH3 moiety on 4a–c assisted by DABCO leads to the hybrid phospholyl(diphenylphosphino)methanes 5a–c. Compounds 4 and 5 were fully characterized by multinuclear NMR spectroscopy (1H, 31P, 13C, 11B), mass spectrometry, and elemental analysis, and the X-ray crystal structures of 4a,c and 5a,b have been established. Ligands 5a,b were used...

The CO-bubbling effect in cycloisomerization reactions of enynes derived from monoterpenes has been studied using PtCl2, [Rh2Cl2(CO)4] and AuCl3 as catalytic systems. All the precursors are efficient catalysts for the cycloisomerization of O-tethered enynes. The reaction proceeds through exo-dig and endo-dig pathways, which are consistent with the exclusive coordination of the alkyne triple bond to the metal center. The CO ligand not only increases the reaction rates but also induces significant variations in the two reaction pathways. Notably, this effect is also strongly dependent on the nature of the starting enyne. Copyright © 2011 John Wiley & Sons, Ltd.

Carbon–carbon coupling catalyzed by transition metals represents a powerful synthetic method to have an access to organic molecules, especially when they present a significant complexity. The strategy to transform abundant and not expensive reactants into products of pharmaceutical interest by the appropriate catalytic way is of fundamental interest, provided that high conversion rates and selectivities can be gained. During the past decade, considerable progress has been made to transform a simple alkene into an aldehyde by carbonylation, to condense it with an NH function-containing molecule present in the medium, and to hydrogenate the resulting imine or enamine into the relevant amine. Rhodium complexes are able to catalyze this series of reactions and be an efficient synthetic tool to produce rather sophisticated amines in one-pot reactions under mild conditions of pressure and temperature. In the future, the production of various amines required by the industry of fine chemicals looks attractive by means of this catalytic method.

Pyridine-based N-phosphanylamidine ligands i-Pr2N–C(pyr) N–PR2 (R = Ph (3), i-Pr (4)) were synthesized and fully characterized by NMR spectroscopy and X-ray crystallography. Mononuclear rhodium complexes 7 and 8 were obtained in one step from the [RhCl(COD)]2 dimer and the monodentate ligands 1 and 2. Their single-crystal X-ray diffraction studies revealed the structural adaptive behavior of the monodentate N-phosphanylamidine ligands 1 and 2 upon k1-P coordination mode in rhodium(I) complexes with the imino nitrogen atom of the amidine function which behaves as a “universal joint”. Compounds 1–4 were evaluated as ligands in the 1-octene and styrene hydroformylation reactions. The results obtained are encouraging and represent the first report on the use of N-phosphanylamidine ligands of the type R″2N–C(R′) N–PR2 in catalytic reactions.

The acid-catalyzed rearrangement of two enantiomerically pure epoxides derived from sesquiterpernic himachalenes, which are the main components of the essential oil of the Atlas cedar, has been studied using various Lewis and Bronsted acids. Several new polycyclic compounds have been obtained with different selectivities depending upon the catalysts used and the reaction conditions, and were fully characterized by spectroscopic methods. Mechanisms to explain the formation of the different compounds observed in the reaction mixture have also been proposed.

The cycloisomerisation of an O-tethered enyne derived from nerol has been studied using various catalytic systems such as PtCl 2 , AuCl 3 , {[AuCl(PPh 3 )]/AgPF 6 } and [Rh 2 Cl 2 (CO) 4 ]. Whatever the catalyst used, formal Alder-ene 1,4-dienes were obtained as major products along with cyclopropane and 1,3-diene derivatives, indicating the crucial influence of the structure of the enyne substrate on the course of the reaction. Differences in terms of activity and selectivity nevertheless appeared when moving from Rh- or Pt-based catalysts to Au(I)-based catalysts: mechanistic pathways are proposed to explain these observations.

103Rh NMR represents a powerful tool to assess the global electronic and steric contribution of diphosphine ligands on [Rh(COD)(diphosphine)]+ complexes. In the case of DIOP, BINAP and MeDUPHOS, this approach proved to be more informative than classical CO-stretching frequency measurements. After validation, this method has been extended to a set of seven diphosphines. 103Rh NMR measurements on [Rh(COD)(diphosphine)]PF6 lead to the following order of donor properties: dppe > MeBPE > MeDUPHOS > dppb > DIOP > BINAP > Tol-BINAP. This trend has been validated by DFT in the case of DIOP, BINAP and MeDUPHOS. In conjunction, 31P NMR chemical shift has been shown to reflect the ring constraints of the Rh-diphosphine scaffold. This contribution is a step towards a mechanistic investigation of the catalytic hydrogenation of unsaturated substrates by 103Rh NMR and DFT. Copyright © 2010 John Wiley & Sons, Ltd.

The molecular rearrangement under mild conditions of two epoxides derived from the sesquiterpenic himachalenes has been studied using BF 3 ·Et 2 O as the Lewis acid catalyst. Both reactions are efficient and selective affording in each case one new enantiomerically pure ketone isolated in good yield. Their structures have been fully characterized by spectroscopic methods. Mechanisms for the BF 3 -catalyzed reactions are proposed.

The asymmetric hydrogenation of prochiral imines has been mainly studied on cationic rhodium or iridium complexes and involves the coordination of the nitrogen atom on the metal centre. Oxidative addition of dihydrogen followed by one hydride transfer onto the carbon atom produces a σ-bonded nitrogen-metal intermediate from which reductive elimination occurs with the second hydride to produce the amine. From all these reactivity studies we propose that in an early step a hydrogen atom transfer could occur on the nitrogen atom to generate an iminium species which coordinates the metal centre through the C N double bond. The Shvo catalyst, an active neutral ruthenium(II) complex, presents the particularity to transfer almost simultaneously a proton from the hydroxycyclopentadienyl ligand and a hydride bonded to the metal center. In this case too, we suggest the first proton transfer generates an iminium species. Morever, a few titanium complexes have been shown to catalyze the hydrogenation of imines. Concerning enamines, literature is rather scarce on catalytic success. On the contrary, many studies focused on hydrogenation of enamides, which represent functionalized enamines, and enantiomeric excesses very close to 100% have been obtained. Extensive studies of the effect of the (chiraldiphosphine)Rh + framework on the asymmetric induction have shown that several reversible steps can occur related to the oxidative addition of dihydrogen before or after the coordination of the enamide; the irreversible step directly connected to the asymmetric induction is the formation of the chiral alkyl-rhodium species.

The first dibenzophospholyl(diphenylphosphino)methane−borane hybrid ligand has been prepared from a Pd-catalyzed reaction of (chloromethyl)diphenylphosphine−borane with the dibenzophospholyl anion. This borane precursor is readily synthesized using a promising new reaction of diphenylphosphine−borane with dichloromethane, under phase transfer catalysis (PTC) conditions. The dibenzophospholyl(diphenylphosphino)methane−borane acts as a chelating P−(η2-BH3) ligand to afford an air-stable Rh(I) complex. The X-ray crystal structure of this complex shows complexation of both benzophospholyl and borane moieties.

The methoxycarbonylation of styrene has been studied using Pd(OAc)2/L/acid catalytic systems with L being chiral ferrocene- and biphosphole-based ligands. Good activities are obtained in mild conditions. Chemoselectivities and regioselectivities (up to 98% in favour of the branched isomer) are excellent but enantioselectivities remain moderate (ee up to 17%).

The Rh-catalyzed cycloisomerization of new terpenoid derivatives featuring an O-tethered enyne unexpectedly leads to polycyclic derivatives containing an inner cyclopropane ring or a diene moiety, depending on the structure of the enyne, as observed in the PtCl2-catalyzed processes. Copyright © 2008 John Wiley & Sons, Ltd.

In the diastereoselective cyclocarbonylation of isopulegol and isolimonene catalysed by the non-chiral [PdCl 2 L 2 ] palladium complexes (L = PPh 3 , L 2 = bis(diphenylphosphino)-butane or -ferrocene), the diastereoisomeric excess is enhanced by a factor of 1.5–2 when toluene is substituted by chloro-solvents. A less significant effect is noted when using more coordinating solvents such as acetonitrile and THF. In chloro-solvents reaction rates are faster than in toluene, isopropanol, acetonitrile or THF.

Pure natural monoterpenes were evaluated in vitro for their antiplasmodial activities against Plasmodium falciparum. Chemically modified terpenes were also tested to see whether the introduction of an alkyne, a cyclopropane, a diene, or a cyclopentenone moiety had an influence on the biological activity. The IC(50) obtained on a chloroquine-resistant strain of Plasmodium (FcM29-Cameroon) showed moderate activity, but with the alkyne and the cyclopentenone derivatives showing a promising enhancement of activity compared with the parent molecules. On the contrary, no antifungal activity was found in vitro using Candida albicans. Given the observed antiplasmodial activity of some of these modified monoterpenes, new monoterpene derivatives could be the basis for new antimalarial drugs to be researched.

International audience; Palladium plays an almost exclusive role as catalyst in the alkoxycarbonylation of various substrates to produce esters or lactones, by incorporation of CO and a alcohol. The coordination sphere can be adapted by introduction of mono- or bidentate phosphorus-containing ligands, providing efficient tools to obtain with high turnovers, regio- and even enantioselectivities the incorporation of a COOR function onto a carbon atom. The use of CO, surrogates such as formates or even carbon dioxide are explored to operate this reaction. Adapted catalytic systems have been designed, sometimes with the assistance of microwave irradiation, to have an immobilization in Ionic Liquids, or scCO2, or on various supports. Even if less expensive metals than palladium are explored to provide comparable performances, green efficient tools are at the disposal of chemists leading to bulk and fine products as well.

International audience; The cyclocarbonylation of homoallylic alcohols, derived from α-atlantone, catalysed by [Pd(Cl2)L2]/SnCl2] system, afforded new γ and δ lactones as the main products with high selectivities. The regiochemical control depends on the nature of phosphines involved. Catalysts based on monophosphines with large cone angles such as tricyclohexyl phosphine produce the six-membered ring lactones with selectivities up to 80%, while diphosphines with wide bite angle such as xantphos are found to favor the five-membered ring lactones with up to 99% selectivity. Monocrystals of the γ and δ lactones suitable for X-ray diffraction analysis have been obtained and the stereochemistry of the lactones 5a,a′ and 6 have been elucidated. This study is the first example of an attractive catalytic transformation of one single natural sesquiterpene easily available from bio-renewable resources to obtain either γ- or δ-lactones.

Ferrocenylphosphines added to [Pd(µ-Cl)(η3-C3H5)]2 dimeric precursor produce efficient catalysts to effect the allylic amination of terpenic allylacetates. Particularly convenient are tetrakis(diphenylphosphino)ferrocene and 1,1′-bis(diphenylphosphino)ferrocene, which allow the amination of allylacetates with good to excellent selectivity, and have turnover numbers as high as 80 000, for instance, for the formation of allylaniline. Herein, we report on reactions that selectively transform geranylacetate, nerylacetate, linalylacetate and perillylacetate into the corresponding allylic amines. These preparative methods give facile access to various products of great potential industrial interest. Copyright © 2006 John Wiley & Sons, Ltd.

This paper focuses on the mechanism by which a monoterpene undergoes a cyclocarbonylation reaction catalysed by a palladium complex. Evidence is provided, based on intermediate species observed under pressure or with various ligands, that the catalytic cycle follows a hydride route starting from [Pd(H)(SnCl3)L-2], The [Pd(H)(SnCl3)L-2] complexes (L = PPh3 or PCy3) have been observed for the first time by multinuclear NMR spectroscopy. Cationic hydride complexes or palladium(0) precursors show either no or poor reactivity. Studies related to model platinum complex chemistry have detected an acylplatinum species. Most of the observations have been done on the cyclocarbonylation of isopulegol, di-hydromyrcenol or isolimonene into the corresponding lactones or cyclopentanones. The use of dihydromyrcene allowed us to observe the acylplatinum complex and the corresponding elusive acylpalladium species. The co-catalytic role of SnCl2 is also demonstrated.

Highly active Pd/diphosphine catalytic systems incorporating new, air-stable ferrocenyl-furylphosphines allow nucleophilic allylic amination at room temperature with unprecedented turnover frequencies. For instance, in the presence of 0.01 mol % catalyst the coupling of aniline to allyl acetate occurs at a TOF of more than 10,000 h - 1 ; even the addition of the less nucleophile morpholine to allyl acetate is observed with a TOF of 4250 h - 1 . The amination of the sterically demanding geranyl acetate, a monoterpene derivative of interest in the flavour industry, at low catalyst loadings demonstrates the scope of this methodology, which provides in addition noticeable advantages in terms of economical (resource- and energy-saving) and sustainable chemistry (high selectivity, no additive, low metal content, and thus easier purification).

The four complexes [Pd(H)(Cl)L 2 ] and [Pd(H)(SnCl 3 )L 2 ], L = PPh 3 , PCy 3 , have been synthesized and fully characterized by multinuclear NMR. They represent the active species of the hydride palladium-catalyzed alkoxycarbonylation of terminal alkenes. Isolation of the model acylplatinum complex, resulting from the carbonylation of dihydromyrcene, clearly shows that SnCl 2 as co-catalyst produces a SnCl 3 ligand which modulates the metal center electron density.

Three different kinds of representative monoterpenic alcohol are involved in the palladium-catalysed cyclocarbonylation reaction. Lactone formation is shown to occur when cyclic (1), tertiary (3) and primary allylic alcohol (7) functions are reacted, in the presence of CO with [HPd(SnCl3)L2] as the active catalytic species. Good yields and selectivities can easily be reached for isopulegol (1), and dihydromyrcenol (3). However, more modest results are obtained for the functionalization of geraniol into the original lactone (9). This lactone can be largely favoured by using a basic chelating diphosphine ligand such as 1,4-bis(diphenylphosphino)butane. Copyright © 2005 John Wiley & Sons, Ltd.

This review presents the main potentialities provided by a substrate bearing at least one chiral carbon atom which is the source of stereodifferentiation when a catalytic functionalization is performed. This chirality control introduced by the substrate itself is an alternative to the classical strategy of introducing chiral ligands in the coordination sphere of a metal, although the level of diastereoselectivity is lower in the former system. We describe how the substrate can induce asymmetry; several catalytic mechanisms are detailed. This relatively unexplored concept could have potential as abundant bidentate non-chiral ligands can be used to tune the stereocontrol of the substrate functionalization.

Cyclocarbonylation of isolimonene catalyzed by complexes of the type [HPd(SnCl3)L2] provides two cyclopentanone isomers (2a and 2b) containing two new stereogenic centers with a good diastereomeric excess (up to 69 % with L2 = dppf). These results show that chiral phosphane ligands are not necessary to ensure asymmetric induction. The diastereomeric excess is due, in fact, to the substrate itself, assisted by the steric hindrance of the diphosphanes. A full characterization of the two isomers by 1H, 13C and DPFGSE NOE NMR spectroscopy gives all the signal assignations and all the positions of the substituents of interest on the chiral carbon atoms. In order to have a better understanding of the catalytic process, we also present a density functional study of the crucial intermediate species 4 involved in the proposed catalytic cycle. Our calculations show that there is no coordination of the C=C bond in an exo mode. Conversely, we have found a pentacoordinate species with a trigonal bipyramidal geometry in which the C=C bond is coordinated in an endo mode. Selected bond lengths and bond orders are reported. The calculated net charge distribution supports the cyclization process, which proceeds through a C−C(O) and a C−Pd coupling. A β-hydride elimination reaction of 4 provides the two 2a and 2b isomers. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)

The methoxycarbonylation of dihydromyrcenol 1 has been carried out in the presence of the catalytic system [PdCl2(PPh3)2]–SnCl2·2H2O–2PPh3. This study shows that it is possible to reduce the amounts of isomerization of the terminal double bond and the dehydration side-reaction of the tertiary alcoholic function. According to the experimental conditions (PCO=40 or 100 bar, concentration of methanol, experiment duration, temperature) it is possible to orient the reaction towards the three ‘linear’ esters 4, 5, 6, and lactone 8. This latter product has been exclusively obtained when the acidity of the medium is controlled. Nevertheless it is more difficult to obtain one ester from each others.