Search results for "alkane"

Evaluation of acyl coenzyme A oxidase (Aox) isozyme function in the n- alkane-assimilating yeast Yarrowia lipolytica

1999

ABSTRACT We have identified five acyl coenzyme A (CoA) oxidase isozymes (Aox1 through Aox5) in the n -alkane-assimilating yeast Yarrowia lipolytica , encoded by the POX1 through POX5 genes. The physiological function of these oxidases has been investigated by gene disruption. Single, double, triple, and quadruple disruptants were constructed. Global Aox activity was determined as a function of time after induction and of substrate chain length. Single null mutations did not affect growth but affected the chain length preference of acyl-CoA oxidase activity, as evidenced by a chain length specificity for Aox2 and Aox3. Aox2 was shown to be a long-chain acyl-CoA oxidase and Aox3 was found to …

Gene cloning and characterization of an alkane hydroxylase system in the long chain n-alkane- degrader Gordonia sp. SoCg

2008

Modular one-pot synthesis of tetrasubstituted pyrroles from alpha-(alkylideneamino)nitriles.

2007

2,3,4,5-Tetrasubstituted pyrroles have been prepared with high regioselectivity by a formal cycloaddition of alpha-(alkylideneamino)nitriles and nitroolefins followed by elimination of HCN and HNO2. The reaction allows the convergent construction of the pyrrole ring in four steps from a nitroalkane and three aldehydes.

Stereoselective Synthesis of Microcarpalide

2002

The first total synthesis of the naturally occurring nonenolide, microcarpalide, is described. The key step in the synthesis was the ring-closing metathesis of a dienic ester prepared in turn by coupling an acid and an alcohol stereoselectively synthesized from (S,S)-tartaric acid and (R)-glycidol, respectively. [structure: see text]

Qualitative and quantitative analysis of the n-alkanes C9-C17 and pristane in clean air masses

1980

An analytical method was developed for measuring n-alkanes (C9 to C17) and other hydrocarbons in tropospheric air with mixing ratios of a few ppt (10−12) and higher. The hydrocarbons are collected in situ in absorption tubes, carefully protected against contamination and analysed later in the laboratory by gas chromatography. First data are reported for Atlantic air masses at the west coast of Ireland.

Sequence similarity of mammalian epoxide hydrolases to the bacterial haloalkane dehalogenase and other related proteins Implication for the potential…

1994

Direct comparison of the amino acid sequences of microsomal and soluble epoxide hydrolase superficially indicates that these enzymes are unrelated. Both proteins, however, share significant sequence similarity to a bacterial haloalkane dehalogenase that has earlier been shown to belong to the alpha/beta hydrolase fold family of enzymes. The catalytic mechanism for the dehalogenase has been elucidated in detail [Verschueren et al. (1993) Nature 363, 693-698] and proceeds via an ester intermediate where the substrate is covalently bound to the enzyme. From these observations we conclude (i) that microsomal and soluble epoxide hydrolase are distantly related enzymes that have evolved from a co…

Catalytic Functionalization of Methane and Light Alkanes in Supercritical Carbon Dioxide

2014

International audience; The development of catalytic methods for the effective functionalization of methane yet remains a challenge. The best system known to date is the so-called Catalytica Process based on the use of platinum catalysts to convert methane into methyl bisulfate with a TOF rate of 10−3 s. In this contribution, we report a series of silver complexes containing perfluorinated tris(indazolyl)borate ligands that catalyze the functionalization of methane into ethyl propionate upon reaction with ethyl diazoacetate (EDA) by using supercritical carbon dioxide (scCO2) as the reaction medium. The employment of this reaction medium has also allowed the functionalization of ethane, prop…

Synthesis, structural and spectroscopic characterization of the α,ω-diammonioalkane hexabromorhodates( III) [H3N(CH2)xNH3]2[H5O2][RhBr6]Br2 (x = 3, 4…

2002

The reaction of rhodium(III) chloride trihydrate with 1,3-diaminopropane and 1,4-diaminobutane in concentrated hydrobromic acid results in the formation of the bis(α,ω-diammonioalkane) diaquahydrogen(1+) hexabromorhodate(III) dibromides [H3N(CH2)xNH3]2[H5O2][RhBr6]Br2 (x = 3, 4). Dark red single crystals were obtained by diffusion-controlled crystallization at room temperature. Both compounds crystallize in space group type P1̄ and their structures are closely related. In view of crystal engineering they are inorganic-organic hybrid materials built up from octahedral [RhBr6]3−, simple Br− and flexible chain-like [H3N(CH2)xNH3]2+ ions with the [H5O2]+ and further Br− ions incorporated and th…

A Stereocontrolled Protocol to Highly Functionalized Fluorinated Scaffolds through a Fluoride Opening of Oxiranes

2016

A novel selective and substrate-dependent synthetic protocol has been developed towards the synthesis of various fluorine-containing, highly functionalized cycloalkane derivatives. The method involves the stereoselective epoxidation of some unsaturated cyclic beta-amino acid derivatives as model compounds, followed by a regioselective fluoride opening of oxiranes under various conditions with Deoxofluor and XtalFluor-E reagents, thereby offering an insight into this new epoxide opening methodology with fluoride.

Structure Determination of Photoproducts of Anthracenes with (Arylmethoxymethyl) Sidechains

2007

Irradiation of 9-(arylmethoxymethyl)anthracenes 3 leads either to a cyclomer and cyclodimer mixture (3a  4a,5a), to selectively formed dimers (3b  5b), or a selectively formed cyclomer (3c  4c). The [4π+4π]cyclodimerization is under the conditions used a regioselective head-to-tail process. In the crystals of the dimers 5a,b, the sidechains are attached in an antiperiplanar position related to the CC bonds generated in the dimerization. In solutions, however, the structures consist of three rotamers the equilibration of which was studied by temperature-dependent NMR spectra. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)