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This article discusses the development of a method for the intramolecular silylmethylation of aromatic C-H bonds using photoexcited palladium as a catalyst. The reaction allows for the introduction of a methyl or hydroxymethyl group onto complex molecules with associated biological activities. The authors optimized the reaction conditions and investigated the scope and limitations of the reaction, finding that a variety of benzylic alcohol derivatives could be efficiently converted into the corresponding siloxacycles. The authors also demonstrated that the carbon-silicon bond of the siloxacycle could be further modified through protodesilylation or oxidation. [Extracted from the article]

C 1-Symmetric chiral ammonium salt catalysts induced a kinetic resolution of racemic α-nitrolactones through an asymmetric ester–amide exchange reaction. The corresponding amides were obtained with high enantioselectivities and high S (= k fast / k slow) values. This reaction system is a useful approach for obtaining carbocyclic quaternary α-nitroamides as chiral building blocks. [ABSTRACT FROM AUTHOR]

An enantioselective Diels–Alder reaction of 3-nitrocoumarins has been developed. A tryptophan-derived C 1-symmetric organoammonium thiourea catalyst promoted the reaction of 3-nitrocoumarins with Danishefsky's diene to give the corresponding adducts with good enantioselectivity (up to 94% ee). One of the resulting adducts was converted into a chiral carbocyclic quaternary β-amino alcohol. [ABSTRACT FROM AUTHOR]

Organoammonium salts of dipeptide-derived chiral triamines or diamines with TfOH catalyzed the enantioselective 1,3-dipolar cycloaddition reactions of α-acyloxyacroleins with nitrones to give the corresponding adducts in good yields (up to 96%) and with high diastereo- and enantioselectivities (up to 89% ee). Although α-(p -methoxybenzoyloxy)acrolein is rather unstable under the reaction conditions, α-(3-pyrroline-1-carbonyloxy)acrolein is stable enough to be smoothly converted into the corresponding adducts with the aid of the chiral organoammonium salt catalysts. [ABSTRACT FROM AUTHOR]

The O-3-pyrroline-1-carbonyl ( O-Pyroc) group and 3-pyrrolinamide are useful removable protecting groups for the kinetic resolution of racemic ?-hydroxycarboxylic acids, ?-hydroxy?carboxylic acids, 1,2-dicarboxylic acids, and 1,2-diols using the L-histidine-derived bifunctional catalysts. The Pyroc group can be easily introduced from Pyroc chloride. Selective deprotection of the Pyroc group and 3-pyrrolinamide can be carried out via DDQ oxidation followed by hydrolysis using sodium hydroxide, without epimerization. [ABSTRACT FROM AUTHOR]

The design of small but highly functional artificial catalysts is very important for practical organic synthesis. We have �succeeded in the rational design of small and simple catalysts and related reactions based on acid-base combination chemistry. Acid-base combined catalysts can be classified into three types: (i) acid-base combined salt catalysts, (ii) conjugate acid-base catalysts, and (iii) nonconjugate acid-base catalysts. We have systematically developed acid-base combined salt catalysts such as ammonium salts, ate complexes, ion pairs and cation-π complexes, acid-base conjugate catalysts such as metal oxides (monoconjugation) and zinc(II)-3,3′-diphosphinol-BINOLates (triconjugation), and acid-base nonconjugate catalysts like l-histidine-derived sulfonamides. [ABSTRACT FROM AUTHOR]