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A ruthenium(II) catalyst containing an NHC-amine (NHC = Nheterocyclic carbene) ligand (C-NH2) catalyzes the H2-hydrogenation of various esters and lactones at 50 °C and 25 bar of H2 pressure, mild reaction conditions compared with other reported catalysts. A maximum turnover frequency of 1510 h-1 for the hydrogenation of phthalide with a conversion of 96% is achieved in 4 h. DFT calculations suggest a concerted, asynchronous bifunctional mechanism for homogeneous ester hydrogenation; a proton transfer step from the N-H group of a ruthenium hydride-amine complex to the carbonyl group has the largest energy barrier in the catalytic cycle. A surprising observation is that methyl pivalate ( tBuCOOCH3) is hydrogenated much more rapidly than is tert-butyl acetate (CH3COOtBu). This is explained by the energetics of the rate-determining step of the proposed Ru-H/N-H bifunctional mechanism.

A remarkable proline-catalyzed method for the construction of biologically interesting oxygen-bridged tricyclic ketal skeletons was uncovered by starting from a variety of readily available cyclic 1,3-diketones and either 1,4- or 1,5-dicarbonyl substrates. The approach, which mimics a biosynthetic Knoevenagel condensation/[4+2] cycloaddition sequence, establishes a viable synthetic strategy for the efficient formal synthesis of averufin. A remarkable proline-catalyzed Knoevenagel condensation/[4+2] cycloaddition cascade reaction was uncovered for the construction of biologically interesting tricyclic ketal skeletons. This approach mimics a biosynthetic sequence and establishes a viable synthetic strategy for the efficient formal synthesis of averufin.

Herein we report a diaminocyclopentadienone iron tricarbonyl complex catalyzed synthesis of substituted cyclopentane, cyclohexane and cycloheptane compounds using the borrowing hydrogen strategy in the presence of various substituted primary and secondary 1,n diols as alkylating reagents. Deuterium labeling experiments confirm that the diols were the hydride source in this cascade process. This journal is

Pd-catalyzed C(sp3)-H activation of alcohol typically shows β-selectivity due to the required distance between the chelating atom in the attached directing group and the targeted C-H bonds. Herein we report the design of a hemilabile directing group which exploits the chelation of a readily removable benzyl ether moiety to direct Γ- or δ-C-H carbonylation and olefination of alcohols. The utility of this approach is also demonstrated in the late-stage C-H functionalization of β-estradiol to rapidly prepare desired analogues that required multi-step syntheses with classical methods.

Pd-catalyzed C(sp3)-H activation of alcohol typically shows β-selectivity due to the required distance between the chelating atom in the attached directing group and the targeted C-H bonds. Herein we report the design of a hemilabile directing group which exploits the chelation of a readily removable benzyl ether moiety to direct γ- or δ-C-H carbonylation and olefination of alcohols. The utility of this approach is also demonstrated in the late-stage C-H functionalization of β-estradiol to rapidly prepare desired analogues that required multi-step syntheses with classical methods.

The invention provides a method for synthesizing diene compounds based on an aldehyde-ketone condensation reaction. The method comprises the following steps: firstly, under the action of a condensation catalyst, performing a condensation reaction on ketone compounds and aldehyde compounds to obtain condensation products; then, under the action of a reduction catalyst, performing a reduction reaction on the condensation products obtained in the previous step to obtain reduction products; under the action of a catalyst, performing a dehydration reaction on the reduction products obtained in theprevious step to obtain the diene compounds. According to the method, ketone, aldehyde as well as homologues of ketone and aldehyde which are cheap and easy to obtain can be used as raw materials forsynthesizing the diene compounds such as butadiene, piperylene as well as homologues of butadiene and piperylene, experimental conditions are mild, the operation is simple, and a large-scale synthesisprospect is achieved.

Bimetallic catalysts based on nonprecious transition metals have attracted increasing attention because of their unique synergistic effects in catalytic reactions, but the understanding of the nature of synergistic effects and their roles in a specific hydrogenation reaction remains lacking. Herein, a series of bimetallic CuxCoy/Al2O3 (x/y = 5:1, 2:1, 1:1, 1:2, 1:5) nanocomposite catalysts were fabricated via the successive calcination and reductive activation process of layered double hydroxide precursors. Their catalytic performance in the selective hydrogenation of bioderived ethyl levulinate to 1,4-pentanediol (1,4-PeD) depended sensitively on the chemical composition of bimetallic CuCo catalysts. The optimal bimetallic Cu2Co1/Al2O3 catalyst exhibited markedly improved catalytic activity and selectivity compared to monometallic Cu/Al2O3, as confirmed by its lower apparent activation energy barrier of 65.1 kJ mol-1 of the rate-determining step and its high selectivity of 93% to 1,4-PeD. Detailed characterization analyses and intrinsic catalytic studies revealed that the presence of CoOx species in the bimetallic CuxCoy/Al2O3 catalysts enhanced the metallic Cu dispersion and H2 activation ability. More importantly, the strong electronic interaction at the interface of Cu and adjacent CoOx species modified the chemical states of Cu species to create proper surface Cu0/Cu+ distributions and, particularly, provided synergic catalysis sites of Cu and electron-deficient CoOx species, which was primarily responsible for the excellent catalytic performance of bimetallic CuCo catalysts. The bimetallic CuCo catalysts exhibited good stability in both batch and fixed-bed continuous flow reactions. Furthermore, present CuCo nanocomposite catalyst could be applied to the highly selective hydrogenation of other carboxylic esters and lactones to synthesize valuable C4, C5, and C6 diols.

Abstract A novel highly regioselective, fluoride-catalyzed hydrosilylation of β-hydroxy epoxides has been developed. The reaction is modular and applicable to the synthesis of a broad range of 1,4-diols. Fluoride is crucial for two reasons: First, it promotes the formation of a silyl ether (which contains a Si-H bond) and, second, it enables ring opening by an intramolecular SN2 reaction through activation of the silane. The reaction can be performed under air. A modular, convergent, and stereoselective synthesis of 1,4-diols by epoxide hydrosilylation has been developed (see scheme). The reaction occurs under fluoride catalysis, is high yielding, highly regioselective, and can be carried out on a large scale.

Metal-free homoallylic oxygen-directed intramolecular hydroboration is reported. Regioselectivities from 20:1 to 82:1 favoring the 1,3-dioxy-substituted products have been achieved using Me2S·BH3/TfOH followed by standard oxidative workup. Branching at the C5 position improves regioselectivity. Copyright

The regioselectivity of nuclcopbilic ring opening of some 3,4-epoxy and 3,4-aziridino alcohols has been studied. The nucleophiles chosen were complex hydrides (LiAlH4, Red-Al and DIBAL) and Lipshutz- or Gilman-type organocuprate reagents. The C-4 substituent in the substrates was varied in order to study steric and electronic effects on the ring opening reactions. For alkyl substituents at C-4, most of the results can be explained on the basis of intramolecular delivery of the nucleophile to C-3 via a six-membered transition state, leading to 1,4-diols or 1,4-amine alcohol derivatives. In general, the epoxy alcohols gave poorer regioselectivity than the N-tosyl aziridino alcohols, for which selectivities of >95:5 were routinely obtained. The activating effect of a phenyl group at C-4 led to a switch in regiochemistry, with the 1,3-diol or 1,3-amino alcohol derivative as the major product.

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As part of our efforts to identify volatile decomposition products in used frying oils, a series of 4- and 5-oxoaldehydes were synthesized, purified, and characterized by gas chromatography, gas chromatography-mass spectrometry, gas-chromatography-Fourier transform infrared spectrometry, and nuclear magnetic resonance spectrometry.Oxoaldehydes have been proposed as possible precursors of alkylfurans, which have potential anticancer effects.In a model reaction 4-oxononanal was refluxed in hexane for 40 days and only trace amounts of 2-pentylfuran were produced, suggesting that it is not a major precursor of the furan.The volatile constituents of used frying oils obtained from commercial food processors were studied, and 4-oxohexanal, 4-oxooctanal, 4-oxononanal, and 4-oxodecanal were identified.Keywords: Oxoaldehydes; odor threshold; frying oil

Eight defined primary and secondary alkylhydroperoxides were decomposed in n-alkanes as the solvent, mostly in the presence of manganese stearate.In all cases the corresponding alcohols and carbonyl compounds were formed as the main products with yields of 60-90percent.Besides, difunctional products were formed by an intramolecular H-transfer in the alkoxy radicals corresponding to the starting hydroperoxides.Products possibly formed by an intramolecular H-transfer in the corresponding alkylperoxy radical could be found only in the case of 4-methyl-2-hydroperoxy pentane.The amount of products formed by intramolecular H-transfer depended on the nature of the C-H bond in δ-position to the original hydroperoxy group and lay between 4percent (primary C-H in the case of 4-hydroperoxy heptane) and 13percent (tertiary C-H in the case of 2-hydroperoxy-5-methyl hexane) with respect to the starting hydroperoxide.The amount of products formed by oxidative attack of the alkoxy and alkylperoxy radicals at the normal paraffins used as the solvents was unexpectedly low (always less than 10percent with respect to the starting hydroperoxide).An increment system is proposed for the calculation of 13C-nmr shifts in alkyl hydroperoxides.

We have developed a three-stage scheme for the preparative synthesis of 2-substituted tetrahydrofurans from allyl halides and aldehydes to give the first stage - a Grignard reaction - mixed alkoxides, which on treatment with acetic anhydride are converted to 4-acetoxy-1-alkenes.Addition of hydrogen bromide to the latter contrary to Markownikoff's rule gives 4-acetoxy-1-bromoalkanes, which as a result of hydrolysis form 2-R-tetrahydrofurans.

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Methyl 3-methyl-8-hydroxy-4-decenoate, a new C10 fatty acid methyl ester, was isolated and characterized from Aspergillus niger var.Tieghem.The chemical synthesis of this compound has also been achieved.Other compounds characterized from A. niger were phenylethanol, phenylacetic acid, phenoxyacetic acid, p-methoxyphenylacetic acid, mannitol and citric acid.All compounds except mannitol, inhibited the germination of cress and lettude seeds.Antifungal bioassay of the above compounds on Cladosporium herbarum showed activity except for the C10 fatty acid methyl ester, mannitol and citric acid.Key Word Index - Aspergillus niger; fungus; methyl 3-methyl-8-hydroxy-4-decenoate; phenylethanol; phenylacetic acid; phenoxyacetic acid; p-methoxyphenylacetic acid; mannitol; citric acid.

Valeric, caproic, and heptanoic acid and their methyl esters were oxidizied at 140 deg C by molecular oxygen.The oxidation mixtures were reduced by LiAlH4, and the mono- and dihydroxy compounds formed were analyzed gaschromatographically.From the results obtained one can conclude that nonbranched aliphatic acids and their methyl esters are attacked by the chain-carrying peroxy radicals at the different C-H bonds with almost the same regioselectivity as normal paraffins.Only the β- and to a smaller extent the α-positions are desactivated by the neighbouring carboxylic group.