29275-83-0Relevant academic research and scientific papers
Amine-Urea-Mediated Asymmetric Cycloadditions between Nitrile Oxides and o-Hydroxystyrenes by Dual Activation
Suga, Hiroyuki,Hashimoto, Yohei,Toda, Yasunori,Fukushima, Kazuaki,Esaki, Hiroyoshi,Kikuchi, Ayaka
supporting information, p. 11936 - 11939 (2017/09/06)
The first example of asymmetric 1,3-dipolar cycloadditions between nitrile oxides and o-hydroxystyrenes, mediated by cinchona-alkaloid-based amine-ureas is reported. The method is based on a dual activation involving both LUMO and HOMO activations. In addition to the stoichiometric asymmetric induction, a catalytic amount of amine-urea enables the cycloadditions to proceed in an enantioselective manner. Computational studies strongly support the HOMO activation of o-hydroxystyrenes and LUMO activation of nitrile oxides by hydrogen-bonding interactions with the Br?nsted acid/base bifunctional catalyst.
Boosting effect of ortho-propenyl substituent on the antioxidant activity of natural phenols
Marteau, Clémentine,Guitard, Romain,Penverne, Christophe,Favier, Dominique,Nardello-Rataj, Véronique,Aubry, Jean-Marie
supporting information, p. 418 - 427 (2015/10/19)
Seven new antioxidants derived from natural or synthetic phenols have been designed as alternatives to BHT and BHA antioxidants. Influence of various substituents at the ortho, meta and para positions of the aromatic core of phenols on the bond dissociation enthalpy of the ArO-H bond was evaluated using a DFT method B3LYP/6-311++G(2d,2p)//B3LYP/6-311G(d,p). This prediction highlighted the ortho-propenyl group as the best substituent to decrease the bond dissociation enthalpy (BDE) value. The rate constants of hydrogen transfer from these phenols to DPPH radical in a non-polar and non-protic solvent have been measured and were found to be in agreement with the BDE calculations. For o-propenyl derivatives from 2-tert-butyl-4-methylphenol, BHA, creosol, isoeugenol and di-o-propenyl p-cresol, fewer radicals were trapped by a single phenol molecule, i.e. a lower stoichiometric number. Reaction mechanisms involving the evolution of the primary phenoxyl radical ArO are proposed to rationalise these effects.
A polymer-supported iridium catalyst for the stereoselective isomerisation of double bonds
Baxendale, Ian R.,Lee, Ai-Lan,Ley, Steven V.
, p. 516 - 518 (2007/10/03)
A polymer-supported iridium catalyst has been prepared and used in the isomerisation of the double bonds in aryl allylic derivatives with excellent trans selectivity and without the need for conventional work-up procedures.
A concise synthesis of carpanone using solid-supported reagents and scavengers
Baxendale, Ian R.,Lee, Ai-Lan,Ley, Steven V.
, p. 1850 - 1857 (2007/10/03)
The synthesis of the natural product carpanone by utilization of polymer supported reagents, eliminating the need for conventional purification techniques was reported. The synthesis and crystal structure of a polymer-supported iridium catalyst for isomerization was also reported. The observations showed that isomerization of electron-rich aromatic compounds by the catalyst resulted in products with predominantly trans alkene geometry. However, the electron-poor derivatives were found to be less prone to rearrangement.
Tobacco smoke chemistry. 2. Alkyl and alkenyl substituted guaiacols found in cigarette smoke condensate.
Arnarp,Bielawski,Dahlin,Dahlman,Enzell,Pettersson
, p. 44 - 50 (2007/10/02)
A series of alkyl and alkenyl substituted guaiacols, which comprise a group of biologically and organoleptically active compounds, have been synthesized. Mass spectra and GC retention times for these have been recorded and compared with those obtained for constituents of a weakly acidic fraction of smoke condensate derived from American blend type cigarettes. On the basis of these results, 25 guaiacols have been identified, 18 of which have not been detected in tobacco smoke condensate previously.
