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

Visible-light-promoted alkylation of electron-deficient alkenes with alkylsilyl peroxides

New insight into the crucial role of bis(dimethylaluminum) sulfate as bidentate Lewis acid has been demonstrated using typical carbonyl allylation and Diels-Alder reaction in comparison with monodentate counterparts. The double coordination phenomenon of bidentate (Me2AlO)2SO2 is characterized with 2,6-dimethyl-γ-pyrone by 13C NMR spectroscopy and Mukaiyama-type Michael addition.

Double Coordination Ability of Bis(dimethylaluminum) Sulfate Toward Carbonyl Substrates.

The conjugate addition of organolithium reagent to α, β-unsaturated ketone has been accomplished with methylaluminum bis(2, 6-di- tert -butyl-4-alkylphenoxide) (MAD and MAT). Here combination of alkyllithium and MAD (or MAT) constitutes an amphiphilic system that allows to exhibit unusual selectivity in the alkylation of enones with alkyllithium.

Unusual Conjugate Addition of Organolithium Reagent to α,β-Unsaturated Ketone.

Meerwein—Ponndorf—Verley Alkynylation of Aldehydes: Essential Modification of Aluminum Alkoxides for Rate Acceleration and Asymmetric Synthesis.

Highly efficient, catalytic enantioselective synthesis of N -arylsulfonyl α-amino nitriles from the corresponding α-amido sulfones has been achieved under toluene–aqueous potassium cyanide biphasic conditions using chiral quaternary ammonium iodide ( R , R , R )- 1 as an effective phase-transfer catalyst. This Strecker synthesis involving the in situ generation of the reactive N -sulfonyl imines is advantageous for the cyanation of the substrates having primary and secondary alkyl substituents.

Keiji Maruoka

Papers

Visible-light-promoted alkylation of electron-deficient alkenes with alkylsilyl peroxides

Double Coordination Ability of Bis(dimethylaluminum) Sulfate Toward Carbonyl Substrates.

Unusual Conjugate Addition of Organolithium Reagent to α,β-Unsaturated Ketone.

Meerwein—Ponndorf—Verley Alkynylation of Aldehydes: Essential Modification of Aluminum Alkoxides for Rate Acceleration and Asymmetric Synthesis.

Advantage of in situ Generation of N‐Arylsulfonyl Imines from α‐Amide Sulfones in the Phase Transfer Catalyzed Asymmetric Strecker Reaction.