Complete Field Guide to Asymmetric BINOL-Phosphate Derived Brønsted Acid and Metal Catalysis: History and Classification by Mode of Activation; Brønsted Acidity, Hydrogen Bonding, Ion Pairing, and Metal Phosphates

Iron Catalysis in Organic Synthesis

Isatins As Privileged Molecules in Design and Synthesis of Spiro-Fused Cyclic Frameworks

Flow chemistry involves the use of channels or tubing to conduct a reaction in a continuous stream rather than in a flask Flow equipment provides chemists with unique control over reaction parameters enhancing reactivity or in some cases enabling new reactions This relatively young technology has received a remarkable amount of attention in the past decade with many reports on what can be done in flow Until recently, however, the question, “Should we do this in flow?” has merely been an afterthought This review introduces readers to the basic principles and fundamentals of flow chemistry and critically discusses recent flow chemistry accounts

The Hitchhiker's Guide to Flow Chemistry

The legacy of Gilbert Newton Lewis (1875-1946) pervades the lexicon of chemical bonding and reactivity. The power of his concept of donor-acceptor bonding is evident in the eponymous foundations of electron-pair acceptors (Lewis acids) and donors (Lewis bases). Lewis recognized that acids are not restricted to those substances that contain hydrogen (Bronsted acids), and helped overthrow the "modern cult of the proton". His discovery ushered in the use of Lewis acids as reagents and catalysts for organic reactions. However, in recent years, the recognition that Lewis bases can also serve in this capacity has grown enormously. Most importantly, it has become increasingly apparent that the behavior of Lewis bases as agents for promoting chemical reactions is not merely as an electronic complement of the cognate Lewis acids: in fact Lewis bases are capable of enhancing both the electrophilic and nucleophilic character of molecules to which they are bound. This diversity of behavior leads to a remarkable versatility for the catalysis of reactions by Lewis bases.

Lewis Base Catalysis in Organic Synthesis

An efficient, asymmetric, catalytic, triple-cascade reaction between α-keto esters and nitroalkenes to construct cyclohexanes with six vicinal stereogenic centers in good yields and with high enantioselectivities has been established. A bifunctional guanidine–amide organocatalyst proved to be useful for the Michael/Michael/Henry sequence through Bronsted base and hydrogen-bonding cooperative catalysis.

Asymmetric Organocatalytic Michael/Michael/Henry Sequence to Construct Cyclohexanes with Six Vicinal Stereogenic Centers

Chiral Lewis acid-catalyzed enantioselective cyclopropanation and C–H insertion reactions of vinyl ketones with α-diazoesters

Chiral N,N'-dioxide-Sc(NTf2)3 complex-catalyzed asymmetric bromoamination of chalones with N-bromosuccinimide as both bromine and amide source.

Highly efficient asymmetric [3 + 2] cycloaddition reactions of thiazolium salts with a variety of electron-deficient 2-π components were achieved by chiral N,N′-dioxide/metal complex catalysts, providing a convenient route to access enantioenriched hydropyrrolo-thiazoles. The oxathiazine and sulfinate could be readily obtained by the oxidation of the hydropyrrolo-thiazole. Moreover, through ingenious collaboration of chiral catalysts with basic additives, the first cascade cycloaddition/rearrangement reaction with β,γ-unsaturated α-ketoesters was realized, and various pyrrolo-[1,4]thiazine derivatives were afforded in excellent results.

Enantioselective [3 + 2] cycloaddition and rearrangement of thiazolium salts to synthesize thiazole and 1,4-thiazine derivatives

A highly efficient asymmetric cascade reaction between keto esters and alkynyl alcohols and amides is reported. The success of the reaction was attributed to the combination of chiral Lewis acid N,N'-dioxide nickel(II) catalysis with achiral π-acid gold(I) catalysis working as an asymmetric relay catalytic system. The corresponding spiroketals and spiroaminals were synthesized in up to 99 % yield, 19:1 d.r., and more than 99 % ee under mild reaction conditions. Control experiments suggest that the N,N'-dioxide ligand was essential for the formation of the spiro products.

Xiaohua Liu

Papers

Asymmetric Organocatalytic Michael/Michael/Henry Sequence to Construct Cyclohexanes with Six Vicinal Stereogenic Centers

Chiral Lewis acid-catalyzed enantioselective cyclopropanation and C–H insertion reactions of vinyl ketones with α-diazoesters

Chiral N,N'-dioxide-Sc(NTf2)3 complex-catalyzed asymmetric bromoamination of chalones with N-bromosuccinimide as both bromine and amide source.

Enantioselective [3 + 2] cycloaddition and rearrangement of thiazolium salts to synthesize thiazole and 1,4-thiazine derivatives

Bimetallic Gold(I)/Chiral N,N′-Dioxide Nickel(II) Asymmetric Relay Catalysis: Chemo- and Enantioselective Synthesis of Spiroketals and Spiroaminals.