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 enantioselective sulfa-Michael-cyclization reaction was developed for the synthesis of 1,5-benzothiazepines with versatile pharmacological activities. The reaction between 2-aminothiophenol and α,β-unsaturated pyrazoleamides gave a direct access to N-H free 1,5-benzothiazepines in the presence of a chiral N,N′-dioxide/Yb(OTf)3 complex. Excellent enantioselectivities (up to 96% ee) and high yields (up to 99%) were obtained for a broad range of substrates under mild reaction conditions. This method provided a facile approach to antidepressant drug R-(-)-thiazesim.

Enantioselective Synthesis of N‐H Free 1,5‐Benzothiazepines

The asymmetric synthesis of γ-alkenyl butenolides was accomplished by conjugated addition of butenolides to alkynones. Both terminal alkynones and nonterminal alkynones were applicable to the N,N′-dioxide–scandium(III) catalytic system. The corresponding products were obtained in good to excellent yields (up to 99%) with high E/Z ratios and high enantioselectivities (up to 98% ee). The novel methods of building both γ-alkenyl butenolides and continuing epoxidation products facilitated constructing core structure of biologically active natural products and synthetic intermediates. Additionally, one-pot Michael addition/epoxidation performed well with our catalytic system.

Highly Efficient Asymmetric Synthesis of Chiral γ-Alkenyl Butenolides Catalyzed by Chiral N,N′-Dioxide–Scandium(III) Complexes

A chiral scandium-complex-catalyzed asymmetric inverse-electron-demand oxa-Diels–Alder reaction of o-quinone methides with fulvenes

Recent Advances in Enantioselective Synthesis of γ-Substituted Butenolides via the Catalytic Asymmetric Vinylogous Reactions

An enantioselective [3 + 2] annulation of donor–acceptor aziridines with aldehydes has been realized using a Nd(OTf)3/N,N′-dioxide/LiNTf2 catalyst system, providing various chiral cis-1,3-oxazolidines in moderate to good yields with high levels of stereocontrol. A relay catalytic process is proposed where LiNTf2 promotes the formation of azomethine ylide intermediates, and a chiral Nd(III)–N,N′-dioxide complex accelerates the asymmetric cycloaddition.

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Xiaohua Liu

Papers

Enantioselective Synthesis of N‐H Free 1,5‐Benzothiazepines

Highly Efficient Asymmetric Synthesis of Chiral γ-Alkenyl Butenolides Catalyzed by Chiral N,N′-Dioxide–Scandium(III) Complexes

A chiral scandium-complex-catalyzed asymmetric inverse-electron-demand oxa-Diels–Alder reaction of o-quinone methides with fulvenes

Recent Advances in Enantioselective Synthesis of γ-Substituted Butenolides via the Catalytic Asymmetric Vinylogous Reactions

Asymmetric [3 + 2] cycloaddition of donor-acceptor aziridines with aldehydes via carbon-carbon bond cleavage.