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A change in regioselectivity has been observed in the hydrogen atom transfer (HAT) reactions from 4-alkyl-N,N-dimethylbenzylamines (alkyl = ethyl, isopropyl, and benzyl) to the phthalimide N-oxyl radical (PINO) by effect of protonation. This result can be rationalized on the basis of an acid-induced deactivation of the C-H bonds alpha to nitrogen toward HAT to PINO as evidenced by the 104-107-fold decrease in the HAT rate constants in acetonitrile following addition of 0.1 M HClO4. This acid-induced change in regioselectivity has been successfully applied for selective functionalization of the less activated benzylic C-H bonds para to the CH2N(CH3)2 group in the aerobic oxidation of 4-alkyl-N,N-dimethylbenzylamines catalyzed by N-hydroxyphthalimide in acetic acid.

The application of the oxidative system composed of a heterogeneous triazolium pre-catalyst, iron(ii) phthalocyanine and air is described for the selective conversion of 5-hydroxymethylfurfural (HMF) into the added-value 5-hydroxymethyl-2-furancarboxylic acid (HMFCA). The disclosed one-pot two-step procedure involved sequential oxidative esterifications of HMF to afford a polyester oligomer having hydroxyl and carboxyl terminal groups (Mw = 389-1258), which in turn was hydrolyzed by a supported base (Ambersep 900 OH) to yield HMFCA in 87% overall yield. The same strategy was adopted for the effective synthesis of ester and amide derivatives of HMFCA by nucleophilic depolymerization of the oligomeric intermediate with methanol and butylamine, respectively. The utilization of the disclosed oxidative system for the direct conversion of HMF and furfural into their corresponding ester, amide, and thioester derivatives is also reported.

Easily accessible 1-hexadecyl-1H-imidazol-3-ium oxalate is highly efficient Bronsted type acidic catalyst for the selected multicomponent one-pot reactions. The short reaction times, easy workup procedures, and green metal-free conditions for the reactions make the protocols more advantageous. Further reactions proceeded smoothly in good to excellent yields with high purity. To investigate mechanism of the multicomponent reactions, DFT calculations were performed. University Scientific Research Projects Unit

Metal–Organic Frameworks (MOFs) are porous crystalline materials that have emerged as promising hosts\ud for the heterogenization of homogeneous organometallic catalysts, forming hybrid materials which\ud combine the benefits of both classes of catalysts. Herein, we report the encapsulation of the\ud organometallic cationic Lewis acidic catalyst [CpFe(CO)2(L)]+ ([Fp–L]+, Cp ¼ h5\ud -C5H5, L ¼ weakly bound\ud solvent) inside the pores of the anionic [Et4N]3[In3(BTC)4] MOF (H3BTC ¼ benzenetricarboxylic acid) via\ud a direct one-step cation exchange process. To conclusively validate this methodology, initially [Cp2Co]+\ud was used as an inert spatial probe to (i) test the stability of the selected host; (ii) monitor the\ud stoichiometry of the cation exchange process and (iii) assess pore dimensions, spatial location of the\ud cationic species and guest-accessible space by single crystal X-ray crystallography. Subsequently,\ud the quasi-isosteric [Fp–L]+ was encapsulated inside the pores via partial cation exchange to form\ud [(Fp–L)0.6(Et4N)2.4][In3(BTC)4]. The latter was rigorously characterized and benchmarked as\ud a heterogeneous catalyst in a simple Diels–Alder reaction, thus verifying the integrity and reactivity of\ud the encapsulated molecular catalyst. These results provide a platform for the development of\ud heterogeneous catalysts with chemically and spatially well-defined catalytic sites by direct exchange\ud of cationic catalysts into anionic MOFs.

Two anaerobic, benzaldehyde-converting bacteria were isolated from an anaerobic upflow anaerobic sludge bed (UASB)-reactor treating potato starch waste water. Strain BOR-Y-T converted benzaldehyde to benzoate and benzylalcohol in approximately equimolar concentrations. Benzaldehyde conversion did not support growth. Strain BOR-Y-T was Gram-positive and rod-shaped, and its cells were slightly thickened in the middle. The strain was a mesophilic spore-former that grew between 15 and 40 degreesC, with optimum growth at 30-37 degreesC. The optimum pH for growth was pH 7(.)0. Strain BOR-Y-T grew on a wide range of carbohydrates and some other carbon sources including yeast extract, cysteine and serine. The G + C content of its DNA was 42 mol%. According to physiological characteristics and 16S rRNA gene sequence analysis, confirmed by DNA-DNA hybridization with its phylogenetic neighbours, strain BOR-Y-T belongs to a novel genus of cluster XII of the clostridia, namely Soehngenia; the name Soehngenia saccharolytica is proposed for the type species (type strain BOR-Y-T = DSM 12858(T) ATCC BAA-502(T)). Strain BR-10(T) reduced benzaldehyde to benzylalcohol. This conversion was coupled to growth. In a medium containing yeast extract, the presence of benzaldehyde resulted in the accumulation of more than twofold more cells. Strain BR-10(T) was a Gram-positive organism that was characterized by oval- or rod-shaped cells with oval ends, which occurred singly, in pairs or sometimes in chains. The strain was moderately thermophilic and grew between 20 and 60 degreesC, with optimum growth at 45 degreesC. The optimum pH for growth was between pH 7(.)0 and 7(.)5. Strain BR-10(T) grew on a wide range of carbon sources including carbohydrates, yeast extract, casein and some amino acids. The G + C content of its DNA was 32 mol%. As determined by 16S rRNA gene sequence analysis, strain BR-10(T) represents a novel species of cluster XIVa of the clostridia; the name Clostridium amygdalinum is proposed for this novel species (type strain BR-10(T) = DSM 12857(T) = ATCC BAA-501(T)).

The tetrabutylammonium (TBA) salts of the Keggin-type polyoxotungstates with general formula [XW11M(H2O)O-39]((n-m)-), where X = P, B or Si and M = Mn, Fe or Co, were evaluated as catalysts in the oxidation of styrene, alpha-methylstyrene, p-methylstyrene, alpha,p-dimethylstyrene, p-chlorostyrene, p-nitrostyrene, and p-methoxystyrene under mild conditions, using aqueous H2O2 as an eco-sustainable oxidant. In this study, the influence of the catalysts and of the different styrene substituents on the oxidation reaction profile was evaluated in terms of conversion and selectivity. For all the performed catalytic studies, the main product results from the oxidative cleavage of the vinyl double bond, except in the case of the oxidation of p-methoxystyrene catalysed by BW11Mn, for which p-methoxyphenol is the main product. The catalysts BW11Mn and SiW11Co give rise to 100% conversion for almost all of the substrates, excluding p-methoxystyrene and p-nitrostyrene for both catalysts and alpha,p-dimethylstyrene only in the case of BW11Mn. The selectivity for C=C cleavage products resulting from the oxidative cleavage of the vinyl double bond can be as high as 98%, reaching 98% conversion for p-nitrostyrene when SiW11Co was used as a catalyst. Possible pathways are discussed and the oxidation of a few presumed intermediates was carried out. The systematic study of several substituted styrene derivatives suggests a possible reactivity order for these compounds in the catalytic system considered.

International audience; Dynamic nuclear polarization surface enhanced NMR (DNP-SENS), Mossbauer spectroscopy, and computational chemistry were combined to obtain structural information on the active-site speciation in Sn-beta zeolite. This approach unambiguously shows the presence of framework Sn-IV-active sites in an octahedral environment, which probably correspond to so-called open and closed sites, respectively (namely, tin bound to three or four siloxy groups of the zeolite framework).

NAD(+)-dependent salicylaldehyde dehydrogenase (SALDH) which catalyzes the oxidation of salicylaldehyde to salicylate was purified form carbaryl-degrading Pseudomonas sp. strain C6. The enzyme was found to be a functional homotrimer (150 kDa) with subunit molecular mass of 50 kDa and contained calcium (1.8 mol/mol of enzyme). These properties were found to be unique. External addition of metal ions showed no effect on the activity and addition of chelators showed moderate inhibition of the activity. Potassium ions were found to enhance the activity significantly. SALDH showed higher affinity for salicylaldehyde (K-m=4.5 mu M) and accepts mono-as well as di-aromatic aldehydes; however it showed poor activity on aliphatic aldehydes. Chloro-/nitro-substituted benzaldehydes were potent substrate inhibitors as compared to benzaldehyde and 3-hydroxybenzaldehyde, while 2-naphthaldehyde and salicylaldehyde were moderate. The kinetic data revealed that SALDH, though having broad specificity, is more efficient for the oxidation of salicylaldehyde as compared to other aromatic aldehyde dehydrogenases which gives an advantage for Pseudomonas sp. strain C6 to bioremediate carbaryl and other aromatic aldehydes efficiently.

International audience; (-)-Ephedrine, used as a model beta-amino alcohol, was covalently anchored on mesoporous micelle templated aluminosilicates (Al-MTS) through nucleophilic substitution of halogenoalkyl(aryl)silane chains previously grafted on the surface. The covalent grafting was performed either by silylation (method a) or b Surface sol-gel (method 6). The latter method provided higher loading. However, the higher loading lowers the resulting mesoporous volume. The coupling alkyl halide moiety was then substituted with (1R,2S)-(-)-ephedrine. Used as chiral auxiliaries in the heterogeneous enantioselective catalysis of the alkylation of benzaldehyde by diethylzine, these materials showed properties which depend mainly on the grafting method. The best results (activity, enantioselectivity) were obtained with catalysts prepared from Supports featuring high initial pore diameter. The effect of the regular porosity on the efficiency and enantioselectivity was shown. Dilution of catalytic sites by alkyl groups and rigidification of the linker were also studied.

Racemic alpha-epimerizable and unfunctionalized aldehydes have been converted into enantiomerically enriched mixtures through a sequence of (i) a conversion into the diastereoisomeric 3-substituted 1-phenyl-2,3-dihydro-1H-naphtho[1,2-e][1,3]oxazines by reaction with the (R)- or (S)-1-(alpha-aminobenzyl)-2-naphthol (Betti's base), (ii) an acid promoted crystallization-induced diastereoisomer transformation (CIDT), and (iii) a clean cleavage of the dihydro-1,3-naphthoxazinic ring of the enriched diastereoisomer, easily collected by filtration, allowing the recovery of the enantiomerically enriched aldehydes and the chiral auxiliary.