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

1,8‐Bis(allylstannyl)naphthalene Derivatives as Neutral Allylation Agents: Rate Acceleration by Chelation‐Induced Lewis Acidity

A new bimetallic approach using dibenzofuran derivative as a requisite spacer has been introduced to achieve high asymmetric induction in the addition of diethylzinc to aldehydes with otherwise ineffective amino alcohol residue.

A convergent, homochiral bis(amino alcohol) for obtaining high enantioselectivity in the addition of diethylzinc to aldehydes

Double coordination ability of bis(dimethylaluminum) sulfate toward carbonyl substrates

An asymmetric synthesis of cyclic amino acids having piperidine and azepane core structures was realized starting from readily available glycine and alanine esters by combination of phase-transfer catalyzed asymmetric alkylation and subsequent reductive amination.

/pdf/stereoselective-synthesis-of-cyclic-amino-acids-via-2aqu4o3uf3.pdf

Stereoselective synthesis of cyclic amino acids via asymmetric phase-transfer catalytic alkylation

A new type of optically pure primary amino aromatic Tf-amide organocatalyst can be easily prepared from 8-amino-1-tetralone, and its chemical behavior was investigated in the context of asymmetric aldol and Mannich reactions. Most notably, the asymmetric aldol reaction proceeded smoothly in brine.

/pdf/design-of-new-amino-tf-amide-organocatalysts-environmentally-3u3cppnd75.pdf

Keiji Maruoka

Papers

1,8‐Bis(allylstannyl)naphthalene Derivatives as Neutral Allylation Agents: Rate Acceleration by Chelation‐Induced Lewis Acidity

A convergent, homochiral bis(amino alcohol) for obtaining high enantioselectivity in the addition of diethylzinc to aldehydes

Double coordination ability of bis(dimethylaluminum) sulfate toward carbonyl substrates

Stereoselective synthesis of cyclic amino acids via asymmetric phase-transfer catalytic alkylation

Design of New Amino Tf-Amide Organocatalysts: Environmentally Benign Approach to Asymmetric Aldol Synthesis