Organic synthesis Lewis acids

Shibasaki, M., Yamada, K.-i., Yoshikawa, N. Lanthanide Lewis acid catalysis. Lewis Acidsin Organic Synthesis - 2 vols. 2000, 2, 911-944. 

Wack, H., Hafez, A.M. etal (2002) Bifunctional asymmetric catalysis a tandem nucleophile/ Lewis acid promoted synthesis of P-lactams. Organic Letters, 4, 1603-1605 Taggi, A.E., Hafez, A.M., Wack, H. eta/. (2002) The development of the first catalysed reaction of ketenes and imines catalytic, asymmetric synthesis of P-lactams. Journal of the American Chemical Society, 124, 6626-6635 Taggi, A.E., Hafez, A.M., Dudding, T. and Lectka, T. (2002) Molecular mechanics calculations as predictors of enantioselectivity for chiral nucleophile catalysed reactions. Tetrahedron, 58, 8351-8356. 

Covalent fluondes of group 3 and group 5 elements (boron, tin, phosphorus, antimony, etc ) are widely used m organic synthesis as strong Lewis acids Boron trifluoride etherate is one of the most common reagents used to catalyze many organic reactions. A representative example is its recent application as a catalyst in the cycloadditions of 2-aza-l,3-dienes with different dienophiles [14] Boron trifluoride etherate and other fluonnated Lewis acids are effective activators of the... 

The [ 2 + 4]-cycloaddition reaction of aldehydes and ketones with 1,3-dienes is a well-established synthetic procedure for the preparation of dihydropyrans which are attractive substrates for the synthesis of carbohydrates and other natural products [2]. Carbonyl compounds are usually of limited reactivity in cycloaddition reactions with dienes, because only electron-deficient carbonyl groups, as in glyoxy-lates, chloral, ketomalonate, 1,2,3-triketones, and related compounds, react with dienes which have electron-donating groups. The use of Lewis acids as catalysts for cycloaddition reactions of carbonyl compounds has, however, led to a new era for this class of reactions in synthetic organic chemistry. In particular, the application of chiral Lewis acid catalysts has provided new opportunities for enantioselec-tive cycloadditions of carbonyl compounds. 

As Lewis acid, titanium tetrachloride, boron trifluoride or ethylaluminum dichloride is often used. The stereochemical outcome of the reaction strongly depends on the Lewis acid used. The Sakurai reaction is a relatively new carbon-carbon forming reaction, that has been developed into a useful tool for organic synthesis. ... 

Chloroaluminate(III) ionic liquid systems are perhaps the best established and have been most extensively studied in the development of low-melting organic ionic liquids with particular emphasis on electrochemical and electrodeposition applications, transition metal coordination chemistry, and in applications as liquid Lewis acid catalysts in organic synthesis. Variable and tunable acidity, from basic through neutral to acidic, allows for some very subtle changes in transition metal coordination chemistry. The melting points of [EMIM]C1/A1C13 mixtures can be as low as -90 °C, and the upper liquid limit almost 300 °C [4, 6]. 

This chapter will mostly deal with the applications of the Lewis-acid-catalyzed Diels Alder reaction to organic synthesis and the influence of Lewis acids on reactivity, stereoselectivity and regioselectivity of the cycloadditions. 

Methylalumoxane as a highly Lewis-acidic reagent for organic synthesis [107]... 

Diiithium 2,2 -methyienebis(4,6-di-fert-butylphenoxide) as a bidentate Lewis acid in organic synthesis [111]... 

Nishiyama H., Motoyama Y. Other Transition Metal Reagents Chiral Transition-Metal Lewis Acid Catalysis for Asymmetric Organic Synthesis in Lewis Acid Reagents 1999 225, Ed Yamamoto H., Pb. Oxford Univ. Press, Oxford Keywords asymmetric Diels-Alder reactions, chiral transition metal Lewis-acid catalysis, asymmetric synthesis... 

Yamamoto H., Yanagisawa A., Ishihara K., Salto S. Designer Lewis Adds for Selective Organic Synthesis Pure Appl. Chem. 1998 70 1507-1512 Keywords Lewis-acid reagents... 

Rare Earth Metal Trifluoromethanesulfonates as Water-Tolerated Lewis Acid Catiaysts Organic Synthesis," Kobavashi. Synlett, 1994, 679... 

Yamamoto H (2000) Lewis Acids in Organic Synthesis. Wiley-VCH, Weinheim... 

Kiindig EP, Saudan CM (2000) In Yamamoto H (ed) Lewis acids in organic synthesis, vol 2. Wiley, Weinheim, pp 597-652... 

Domino reactions are also used in the development of new and potent pharmaceuticals, which is an important target in organic synthesis. The following example by Katoh and coworkers presents an impressive approach to the tetracyclic core structure of the novel anti-influenza A virus agent, stachyflin (1-152), using as key feature a new Lewis acid-induced domino epoxide-opening/rearrangement/cy-... 

Metal Complexes as Lewis-acid Catalysts in Organic Synthesis... 

Lewis-acid-catalyzed reactions often occur with unique reactivity and selectivity, and the reactions proceed under mild conditions. Many Lewis-acid-mediated reactions are now used not only in laboratories but also in industry. This chapter summarizes these Lewis acid-mediated reactions successfully used in organic synthesis they are organized mainly by the element of the Lewis-acid catalyst. Due to limitations of space, the focus is on more recent publications.1-3... 

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