ChemInform Abstract: Catalysis by Lithium Cation: Lithium Trifluoromethanesulfonate as a Substitute for Lithium Perchlorate in Cycloadditions.

Abstract

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Understanding “On-Water” Catalysis of Organic Reactions. Effects of H+ and Li+ Ions in the Aqueous Phase and Nonreacting Competitor H-Bond Acceptors in the Organic Phase: On H2O versus on D2O for Huisgen Cycloadditions

“…There have been extensive studies of the catalytic effects of Li + ions on the Diels–Alder [4 + 2] cycloadditions as well as [2 + 2] cycloadditions and a range of other important reactions, including aldol reactions, Michael reactions, Alder–ene reactions, sigmatropic rearrangements, and Mannich reactions, − Lithium perchlorate in diethyl ether has been widely used but other salts, such as lithium trifluoromethanesulfonate and trifluoromethane sulfonimide in solvents such as acetone and acetonitrile, have also been explored. , In the context of on-water chemistry, it is of particular interest to explore the presence of H + and the related charge intensive Li + ion as additives in the aqueous layer. In Table are shown the results of adding low to high concentrations of HClO 4 and LiClO 4 to the on-water and in-water reactions in Scheme .…”

TiO2 Photocatalysis in Aromatic “Redox Tag”-Guided Intermolecular Formal [2 + 2] Cycloadditions

“…Our reaction design involves the aromatic “redox tag” concept, in which an aromatic ring provides both the oxidant and the reductant in the overall net redox neutral carbon–carbon bond formation reaction. In most cases, the use of LiClO 4 /CH 3 NO 2 electrolyte solution is critical because it exhibits remarkable Lewis acidity, which facilitates the reactions of carbon-centered radical cations with carbon nucleophiles, even unactivated alkenes . Our reaction development is also characterized by the importance of an intramolecular SET process that has recently been presented by Melchiorre as an elegant “electron relay” mechanism .…”