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

The enantioselective tandem reaction of β,γ-unsaturated α-ketoesters with β-alkynyl ketones was realized by a bimetallic catalytic system of achiral AuΙΙΙ salt and chiral N,N'-dioxide-MgΙΙ complex. The cycloisomerization of β-alkynyl ketone and asymmetric intermolecular [4+2] cycloaddition with β,γ-unsaturated α-ketoesters subsequently occurred, providing an efficient and straightforward access to chiral multifunctional 6,6-spiroketals in up to 97 % yield, 94 % ee and >19/1 d.r. Besides, a catalytic cycle was proposed based on the results of control experiments.

Bimetallic Catalytic Asymmetric Tandem Reaction of β‐Alkynyl Ketones to Synthesize 6,6‐Spiroketals

A new and simple fluorescent sensor based on unmodified BINOL was developed. The fluorescence of BINOL could be turned off with high selectivity toward Cu(II) among 27 metal ions. Meanwhile, it was found that BINOL was oxidized to dibenzo[a,kl]xanthen-1-ol (A) by Cu(NO3)2. A new peak appeared at ∼482 nm upon addition of thiol-containing cysteine (Cys), homocysteine (Hcy), and glutathione (GSH). Thus, a cascade recognition of Cu(II) and Cys, Hcy, and GSH are well presented.

Fluorescent Sensor Based on BINOL for Recognition of Cysteine, Homocysteine, and Glutathione

Enantioselective recognition of α-hydroxycarboxylic acids and N-Boc-amino acids by counterion-displacement assays with a chiral nickel(II) complex.

The catalyst in combination with p-cyanobenzoic acid affords thioxo-1-tosylimidazolidine derivatives with high yields and stereoselectivities.

Guanidine organocatalyst for the asymmetric Mannich-type reaction between α-isothiocyanato imide and sulfonyl imines.

The asymmetric inverse-electron-demand hetero-Diels-Alder (HDA) reactions of β,γ-unsaturated α-ketoesters with electron-rich alkenes were investigated, with an N,N'-dioxide/erbium(III) complex employed as the catalyst. Quantitative conversion of the β,γ-unsaturated α-ketoesters and excellent enantioselectivities (up to >99% ee) and diastereoselectivities (up to >99:1 d.r.) were observed for a broad range of substrates by using a 0.5-0.05 mol% catalyst loading under mild reaction conditions. The reaction could be scaled up to the gram scale with the same results. In addition, this was the first application of Er(OTf)(3) to the asymmetric inverse-electron-demand HDA reaction and it behaved as an efficient catalyst. Moreover, the synthetic utility of this methodology was demonstrated with the synthesis of key intermediates of some natural products.

Asymmetric Cycloaddition of β,γ‐Unsaturated α‐Ketoesters with Electron‐Rich Alkenes Catalyzed by a Chiral Er(OTf)3/N,N′‐Dioxide Complex: Highly Enantioselective Synthesis of 3,4‐Dihydro‐2 H‐pyrans

Xiaohua Liu

Papers

Bimetallic Catalytic Asymmetric Tandem Reaction of β‐Alkynyl Ketones to Synthesize 6,6‐Spiroketals

Fluorescent Sensor Based on BINOL for Recognition of Cysteine, Homocysteine, and Glutathione

Enantioselective recognition of α-hydroxycarboxylic acids and N-Boc-amino acids by counterion-displacement assays with a chiral nickel(II) complex.

Guanidine organocatalyst for the asymmetric Mannich-type reaction between α-isothiocyanato imide and sulfonyl imines.

Asymmetric Cycloaddition of β,γ‐Unsaturated α‐Ketoesters with Electron‐Rich Alkenes Catalyzed by a Chiral Er(OTf)3/N,N′‐Dioxide Complex: Highly Enantioselective Synthesis of 3,4‐Dihydro‐2 H‐pyrans