However, since the previous study began with cationic catalysts and no extra charge separation in the activation step and here we wished to perform a Lewis cycle with neutral AlCl3 and Lewis acid catalyzed bromination on aromatic side chain was achieved efficiently by using 1,3-dibromo-5,5-dimethylhydantoin (DBDMH) as a bromination reagent under mild conditions. Lewis acid catalyst, Sc(OTf)3. Relatively thick films were crystalline, whereas the films

Zirconium(IV) chloride showed the highest catalytic activity for the benzylic bromination. used 1 for Diels-Alder reaction using acrylates as dienophiles, to afford the corresponding addition products in high yields under mild conditions. used this motif to activate a Lewis acid cocatalyst, pulling a leaving group off silicon instead of carbon (see the Perspective by Mattson). N-(Trimethylsilyl)bis(trifluoromethanesulfonyl)imide (1) is an analogue of, TMSOTf and TMSN(SO 2 F) 2, which has very low electron density on its silicon atom and acts as powerful Lewis acid catalyst in various reactions.For example, Mathieu et al. In the resultant ion pair, the shape of the catalyst can bias an ensuing reaction to favor just one of two possible mirror-image products. In this reaction, called nitration, the nitro group, LNO 2, is introduced into the benzene ring by electrophilic substitution. Mechanism of Glucose Isomerization Using a Solid Lewis Acid Catalyst in Water † Dr. Yuriy Román‐Leshkov Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125 (USA), Fax: (+1) 626‐568‐8743 Benzene reacts with concentrated nitric acid, usually in the presence of a sulfuric acid catalyst, to form nitrobenzene. The cooperation between Lewis acid and Brønsted acid was also observed for the hydrodeoxygenation of 2,3‐butanediol to butane catalyzed by Cu/zeolites. as chiral Lewis acids1 in a variety of organic transformations including Diels-Alder,2 hetero-Diels-Alder,3 aldol,4 Michael,5 ene,6 and enol amination7 reactions. Analogous to the hydrogen bonding effect, Lewis acids can decrease the HOMO-LUMO gap between diene and dienophile and thereby induce an increase of the rate of the reaction. The mechanism of acid- and base-catalyzed reactions is explained in terms of the Brønsted–Lowry concept of acids and bases as one in which there is an initial transfer of protons from an acidic catalyst to the reactant or from the reactant to a basic catalyst. be induced in organic solvents by coordinating a Lewis-acid catalyst to the activating group of (for normal electron demand Diels-Alder reactions) the dienophile 12. at the same reaction but with a Lewis acid catalyst, to contrast the Lewis and Bronsted mechanisms for the same reaction. This reaction fits the mechanistic pattern of the electrophilic aromatic substitution reaction The Mukaiyama Michael reaction,8 the addition of an enolsilane to an R,â-unsaturated carbonyl induced by a Lewis acid…