In the investigation of efficient chemical transformations, the carbon-carbon bond-forming reactions play an outstanding role. In this context, organocatalytic processes have achieved considerable attention. 1 Beside their facile reaction course, selectivity, and environmental friendliness, new synthetic strategies are made possible. Particularly, the inversion of the classical reactivity (Umpolung) opens up new synthetic pathways. 2 In nature, the coenzyme thiamine (vitamin B1), a natural thiazolium salt, utilizes a catalytic variant of this concept in biochemical processes as nucleophilic acylations. 3 The catalytically active species is a nucleophilic carbene. 4

Organocatalysis by N-Heterocyclic Carbenes

Asymmetric enamine catalysis.

Small-molecule H-bond donors in asymmetric catalysis.

4.2.8. Reductive Coupling 3109 5. Reaction of Aromatic Compounds 3110 5.1. Electrophilic Substitutions 3110 5.2. Radical Substitution 3111 5.3. Oxidative Coupling 3111 5.4. Photochemical Reactions 3111 6. Reaction of Carbonyl Compounds 3111 6.1. Nucleophilic Additions 3111 6.1.1. Allylation 3111 6.1.2. Propargylation 3120 6.1.3. Benzylation 3121 6.1.4. Arylation/Vinylation 3121 6.1.5. Alkynylation 3121 6.1.6. Alkylation 3121 6.1.7. Reformatsky-Type Reaction 3122 6.1.8. Direct Aldol Reaction 3122 6.1.9. Mukaiyama Aldol Reaction 3124 6.1.10. Hydrogen Cyanide Addition 3125 6.2. Pinacol Coupling 3126 6.3. Wittig Reactions 3126 7. Reaction of R,â-Unsaturated Carbonyl Compounds 3127

Organic Reactions in Aqueous Media with a Focus on Carbon−Carbon Bond Formations: A Decade Update

Over the past decade, the most significant, conceptual advances in the field of fluorination were enabled most prominently by organo- and transition-metal catalysis. The most challenging transformation remains the formation of the parent C-F bond, primarily as a consequence of the high hydration energy of fluoride, strong metal-fluorine bonds, and highly polarized bonds to fluorine. Most fluorination reactions still lack generality, predictability, and cost-efficiency. Despite all current limitations, modern fluorination methods have made fluorinated molecules more readily available than ever before and have begun to have an impact on research areas that do not require large amounts of material, such as drug discovery and positron emission tomography. This Review gives a brief summary of conventional fluorination reactions, including those reactions that introduce fluorinated functional groups, and focuses on modern developments in the field.

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Introduction of Fluorine and Fluorine-Containing Functional Groups

High-speed Tishchenko reaction of various aldehydes can be realized by using a bowl-shaped [tris(2,6-diphenylbenzyl)siloxy]dimethylaluminum catalyst, which is readily prepared by treatment of tris(2,6-diphenylbenzyl)silanol with trimethylaluminum.

Bowl-shaped [tris(2,6-diphenylbenzyl)siloxy]-dimethylaluminum catalyst for effecting Tishchenko reaction

PROBLEM TO BE SOLVED: To provide an optically active quaternary ammonium salt exhibiting high stereoselectivity as an axial asymmetry-containing spiro type phase transfer catalyst for an asymmetric alkylation reaction of a glycine derivative even for a small molecule such as methyl iodide or a substrate such as a secondary alkyl halide and a method for producing the same, and an optically active α-amino acid derivative stereoselectively useful as a synthetic intermediate for medicines and agrochemicals and a method for producing the same. SOLUTION: An axial asymmetry-containing spiro type ammonium salt in which a silyl group substituted with an alkyl group or an aryl group on an aromatic ring is introduced is used as the phase transfer catalyst for the asymmetric alkylation reaction of the glycine derivative. COPYRIGHT: (C)2005,JPO&NCIPI

OPTICALLY ACTIVE QUATERNARY AMMONIUM SALT, METHOD FOR PRODUCING THE SAME AND METHOD FOR PRODUCING OPTICALLY ACTIVE α-AMINO ACID DERIVATIVE USING THE SAME

Aluminum Tris(2,6-diphenylphenoxide) (ATPH) as an Efficient and Selective Activator for Inoue Polymerization

Highly enantioselective Michael addition of diethyl malonate to chalcone derivatives has been achieved under mild phase-transfer conditions by the successful utilization of N-spiro C2-symmetric chiral quaternary ammonium bromide 1 as a catalyst, which possesses diarylhydroxymethyl functionalities as a recognition site for the prochiral electrophile. This simple asymmetric Michael addition process was found to be quite effective for various chalcone derivatives, including those with heteroaromatic substituents.

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Importance of Chiral Phase‐Transfer Catalysts with Dual Functions in Obtaining High Enantioselectivity in the Michael Reaction of Malonates and Chalcone Derivatives.

Keiji Maruoka

Papers

Bowl-shaped [tris(2,6-diphenylbenzyl)siloxy]-dimethylaluminum catalyst for effecting Tishchenko reaction

OPTICALLY ACTIVE QUATERNARY AMMONIUM SALT, METHOD FOR PRODUCING THE SAME AND METHOD FOR PRODUCING OPTICALLY ACTIVE α-AMINO ACID DERIVATIVE USING THE SAME

Aluminum Tris(2,6-diphenylphenoxide) (ATPH) as an Efficient and Selective Activator for Inoue Polymerization

Importance of Chiral Phase‐Transfer Catalysts with Dual Functions in Obtaining High Enantioselectivity in the Michael Reaction of Malonates and Chalcone Derivatives.

A New Strategy for Organocatalyzed Asymmetric Synthesis of BINOL Derivatives