32082-32-9Relevant academic research and scientific papers
Rhodium-Catalyzed Hydrocarboxylation of Olefins with Carbon Dioxide
Kawashima, Shingo,Aikawa, Kohsuke,Mikami, Koichi
, p. 3166 - 3170 (2016/07/19)
The catalytic hydrocarboxylation of styrenes derivatives and α,β-unsaturated carbonyl compounds with CO2(101.3 kPa) in the presence of an air-stable rhodium catalyst was explored. The combination of [RhCl(cod)]2(cod = cyclooctadiene) as a catalyst and diethylzinc as a hydride source allowed for effective hydrocarboxylation and provided the corresponding α-aryl carboxylic acids in moderate to excellent yields. In this catalytic process with carbon dioxide, intervention of the RhI–H species, which could be generated from the RhIcatalyst and diethylzinc, was clarified. Significantly, the catalytic asymmetric hydrocarboxylation of α,β-unsaturated esters with carbon dioxide was also performed by employing a cationic rhodium complex possessing (S)-(–)-4,4′-bi-1,3-benzodioxole-5,5′-diylbis(diphenylphosphine) [(S)-SEGPHOS] as a chiral diphosphine ligand. A plausible model for asymmetric induction was proposed by determination of the absolute configuration of the product.
Resorcylic acid lactone biosynthesis relies on a stereotolerant macrocyclizing thioesterase
Heberlig, Graham W.,Wirz, Monica,Wang, Meng,Boddy, Christopher N.
supporting information, p. 5858 - 5861 (2015/02/19)
Zearalenone and radicicol are highly related resorcylic acid lactones with the rare property of having opposite stereochemical configurations of the secondary alcohol involved in lactone formation. The ability of the thioesterases from the zearalenone and radicicol biosynthetic pathways to macrocyclize both d and l configured synthetic substrate analogs was biochemically characterized and showed that both enzymes were highly stereotolerant, macrocyclizing both substrates with similar kinetic parameters. This observed stereotolerance is consistent with a proposed evolution of both natural products from a common ancestral resorcylic acid lactone.
Impact of electronic modification of the chelating benzylidene ligand in cis-dichloro-configured second-generation olefin metathesis catalysts on their activity
Pump, Eva,Poater, Albert,Zirngast, Michaela,Torvisco, Ana,Fischer, Roland,Cavallo, Luigi,Slugovc, Christian
supporting information, p. 2806 - 2813 (2014/06/24)
A series of electronically modified second-generation cis-dichloro ruthenium ester chelating benzylidene complexes was prepared, characterized, and benchmarked in a typical ring-opening metathesis polymerization (ROMP) experiment. The electronic tuning of the parent chelating benzylidene ligand (2-ethyl ester benzylidene) was achieved by substitution at the 4- and 5-positions with electron-withdrawing nitro or electron-donating methoxy groups. The effect of the electronic tuning on the cis-trans isomerization process was studied experimentally and theoretically. Density functional theory calculations clearly revealed the influence of electronic modification on the relative stability between the cis and trans isomers, which is decisive for the activity of the studied compounds as initiators in ROMP.
An easy access to styrenes: Trans aryl 1,3-, 1,4- and 1,5-dienes, and 1,3,5-trienes by Hiyama cross-coupling catalyzed by palladium nanoparticles
Chatterjee, Tanmay,Dey, Raju,Ranu, Brindaban C.
experimental part, p. 1103 - 1110 (2011/07/08)
A convenient and efficient procedure has been developed for the vinylation of aryl-, styrenyl-, cinnamyl- and dienyl-halides by a Pd(0) nanoparticle-catalyzed Hiyama cross-coupling to provide the corresponding dienes and trienes in high yields. The reaction does not require any ligand or co-catalyst, and is carried out using PdCl2 and tetrabutyl ammonium fluoride (TBAF) in THF. Pd nanoparticles are generated in situ and are the active catalytic species in this reaction. A wide range of functionalized styrenes, trans aryl 1,3-, 1,4- and 1,5- dienes, 1,2-, 1-3 and 1,4-bis(1,3-dienes), and 1,3,5-trienes can be obtained by this procedure. The Royal Society of Chemistry and the Centre National de la Recherche Scientifique 2011.
Synthesis of macrolide-saccharide hybrids by ring-closing metathesis of precursors derived from glycitols and benzoic acids
Matos, Marie-Christine,Murphy, Paul V.
, p. 1803 - 1806 (2007/10/03)
The benzomacrolactone structural motif is a privileged or evolutionarily selected scaffold that codes properties required for binding to proteins and novel analogues thereof may provide a source of new bioactive compounds. Saccharides are also privileged structures, with (amino)sugars, imino-sugars, and sugar amino acids being applied as scaffolds for the development of nonpeptidal peptidomimetics. The syntheses of novel polyhydroxylated oxamacrolides, structural analogues of natural polyketide derived macrolides, are described herein, providing a basis for their development as scaffolds. The syntheses were carried out from benzoic acids and appropriately protected D-mannitol or D-sorbitol (D-glucitol). Ring-closing metathesis was applied in the macrocyclization step with high E-alkene selectivities being observed. X-ray crystal structures, for two polyhydroxylated derivatives, show that the macrocyclic rings display similar conformations. In addition, intermolecular hydrogen-bonding networks are observed in the lattices.
Vinylation of aryl bromides using an inexpensive vinylpolysiloxane
Denmark, Scott E.,Butler, Christopher R.
, p. 63 - 66 (2007/10/03)
(Chemical Equation Presented) A mild and general method for the palladium-catalyzed vinylation of aryl bromides has been developed. The use of tetrabutylammonium fluoride (TBAF) as the activator and an inexpensive and nontoxic vinyl donor, 1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane (D4V, 1), allows for a general and high-yielding preparation of substituted styrenes.
Pd/P(t-Bu)3: A mild and general catalyst for stille reactions of aryl chlorides and aryl bromides
Littke, Adam F.,Schwarz, Lothar,Fu, Gregory C.
, p. 6343 - 6348 (2007/10/03)
Pd/P(t-Bu)3 serves as an unusually reactive catalyst for Stille reactions of aryl chlorides and bromides, providing solutions to a number of long-standing challenges. An unprecedented array of aryl chlorides can be cross-coupled with a range of organotin reagents, including SnBu4. Very hindered biaryls (e.g., tetra-ortho-substituted) can be synthesized, and aryl chlorides can be coupled in the presence of aryl triflates. The method is user-friendly, since a commercially available complex, Pd(P(t-Bu)3)2, is effective. Pd/P(t-Bu)3 also functions as an active catalyst for Stille reactions of aryl bromides, furnishing the first general method for room-temperature cross-couplings.
Potassium organotrifluoroborates: New partners in palladium-catalysed cross-coupling reactions
Darses, Sylvain,Michaud, Guillaume,Genet, Jean-Pierre
, p. 1875 - 1883 (2007/10/03)
The preparation of various potassium organotrifluoroborates bearing either aryl, alkenyl, or alkynyl substituents is described. These stable salts are shown to be very efficient partners in palladium-catalysed cross- coupling reactions with arenediazonium salts, affording biaryl and styrene derivatives in high yields.
