نتایج جستجو برای: isomerisation

تعداد نتایج: 423  

Journal: :Chemical communications 2014
J Messner P S Schulz N Taccardi Sven Kuhlmann P Wasserscheid

The isomerisation reaction of 1,4-dichlorobenzene leading to the thermodynamically favoured and technically desired 1,3-dichlorobenzene has been studied comparing highly acidic chloroaluminate melts with organic imidazolium and alkali metal ions. Interestingly, the inorganic melts show much higher reactivity and full recyclability if small AlCl3 losses are compensated and the reaction is carrie...

Journal: :Organic & biomolecular chemistry 2009
Katja Krämer Jan Deska Christina Hebach Uli Kazmaier

Chelated enolates are versatile nucleophiles for palladium-catalysed allylic alkylations. Even with complex allylic substrates the reaction proceed without significant isomerisation. This allows the stereoselective introduction of polyhydroxylated allylic sidechains into amino acids and peptides with retention of the olefin geometry.

Journal: :Dalton transactions 2012
Antje Modrow Dordaneh Zargarani Rainer Herges Norbert Stock

For the first time an azo functionality was covalently introduced into a MOF by post-synthetic modification. The reaction of Cr-MIL-101-NH(2) with p-phenylazobenzoylchloride (1) and 4-(phenylazo)phenylisocyanate (2) as the reactants led to the compounds Cr-MIL-101_amide and Cr-MIL-101_urea, with the azo groups protruding into the mesoporous cages. XRPD and N(2) sorption measurements confirm the...

Journal: :Phytochemistry 2008
Soad A L Bayoumi Michael G Rowan Ian S Blagbrough John R Beeching

Two to three days after harvesting, cassava (Manihot esculenta Crantz) roots suffer from post-harvest physiological deterioration (PPD) when secondary metabolites are accumulated. Amongst these are hydroxycoumarins (e.g. scopoletin and its glucoside scopolin) which play roles in plant defence and have pharmacological activities. Some steps in the biosynthesis of these molecules are still unknow...

2015
David McKay Stuart A. Macgregor Alan J. Welch

Institute of Chemical Sciences, School Heriot-Watt University, Edinburgh, EH14 4 uk; Fax: +44 (0)1314513180; Tel: +44 (0)13 † Electronic supplementary information (E isomerisation (17-79_isom.avi), ortho-carbor and meta-carborane reduction (meta-ca proles; computed Cartesian coordinates a 10.1039/c5sc00726g ‡ Present address: School of Chemistry, S Andrews, Fife, KY16 9ST, UK. Cite this: Chem....

2017
Yoann Coquerel Paul Brémond Jean Rodriguez

The palladium hydride-iminium complex generated from Pd/C and triethylamine catalyses the isomerisation of allylic alcohols into carbonyl compounds, and Pd/C catalyses the conjugate reduction of activated double bonds using triethylamine as the source of the two newly incorporated hydrogen atoms via the same complex.

Journal: :Physical chemistry chemical physics : PCCP 2014
Burkhard Zietz Erik Gabrielsson Viktor Johansson Ahmed M El-Zohry Licheng Sun Lars Kloo

Organic solar cell dyes containing the most common anchoring group, cyanoacrylic acid, are shown to be photolabile and undergo photoisomerization. This may have significant consequences for dye-sensitized solar cells, as isomerisation competes with electron injection and leads to modifications of the dye and surface arrangement.

Journal: :Beilstein Journal of Organic Chemistry 2007
Matthew L Clarke Charlotte ES Jones Marcia B France

Intramolecular carbonyl ene reactions of highly activated enophiles can be catalysed by H-bonding thio-ureas to give tertiary alcohols in high yields without extensive isomerisation side products. An asymmetric variant of this reaction was realised using a chiral thiourea but was limited by low enantioselectivity (up to 33% e.e.) and low turnover frequencies.

2015
Lisa Candish Alison Levens David W. Lupton

N-Heterocyclic carbene catalysed redox isomerisation with reduction about the carbonyl has been developed in the transformation of trienyl esters to tetrasubstituted benzaldehydes. The reaction proceeds in good to excellent yield, and in cases that provide 2,20-biaryls, enantioselectivity is observed. Mechanistic studies demonstrate the intermediacy of a cyclohexenyl b-lactone, while implicatin...

Journal: :Berichte der deutschen chemischen Gesellschaft 1895

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