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The enantioselective ketimine–ene reaction is one of the most challenging stereocontrolled reaction types in organic synthesis. In this work, catalytic enantioselective ketimine–ene reactions of 2‐aryl‐3H‐indol‐3‐ones with α‐methylstyrenes were achieved by utilizing a B(C6F5)3/chiral phosphoric acid (CPA) catalyst. These ketimine–ene reactions proceed well with low catalyst loading (B(C6F5)3/CPA=2 mol %/2 mol %) under mild conditions, providing rapid and facile access to a series of functionalized 2‐allyl‐indolin‐3‐ones with very good reactivity (up to 99 % yield) and excellent enantioselectivity (up to 99 % ee). Theoretical calculations reveal that enhancement of the acidity of the chiral phosphoric acid by B(C6F5)3 significantly reduces the activation free energy barrier. Furthermore, collective favorable hydrogen‐bonding interactions, especially the enhanced N−H⋅⋅⋅O hydrogen‐bonding interaction, differentiates the free energy of the transition states of CPA and B(C6F5)3/CPA, thereby inducing the improvement of stereoselectivity. [ABSTRACT FROM AUTHOR]

This account summarizes our recent work on the p K a scales of some frequently used organocatalysts, especially those of hydrogen-bond-donor catalysts and stronger Brønsted acid catalysts. Most of these p K a values were obtained by the Bordwell overlapping indicator method, which is known to provide high accuracy. Linear free-energy relationships associated with p K a values are discussed in relation to understanding of reaction mechanisms. 1 Introduction 2 Single Hydrogen-Bonding Donors 2.1 Proline-Type Organocatalysts 2.2 Cinchona Alkaloids Bearing a Hydrogen-Bonding Donor in the 6′-Position 3 Double-Hydrogen-Bonding Donors 3.1 Thioureas 3.2 Squaramides 3.3 BINOLs 4 Stronger Brønsted Acids 5 N-Heterocyclic Carbenes 6 Summary and Outlook [ABSTRACT FROM AUTHOR]

Free energy relationship (FER) studies to correlate steric parameters with the enantiocatalytic performance of bifunctional tertiary-amine hydrogen-bonding catalysts, including ( S, S)-cyclohexane-1,2-diamine-derived thioureas, Cinchona alkaloid derived thioureas, and ( S, S)-cyclohexane-1,2-diamine-derived squaramides, in Michael reactions revealed that the reactions are much favored by catalysts with less bulky N-substituents. The observed FERs are independent of the chiral scaffold and hydrogen-bond donor, and deepen the understanding of current bifunctional hydrogen-bonding catalysts. Moreover, DFT calculations were performed to interpret the observed high reactivities of thioureas with less bulky substituents. In particular, the computations demonstrated the advantage of a benzyl thiourea catalyst, in which an extra CH ⋅⋅⋅π interaction between catalyst and substrate is the key factor. [ABSTRACT FROM AUTHOR]

An asymmetric 1,6-conjugate addition of thioacetic acid with para-quinone methides has been developed by using chiral phosphoric acid catalysis in the presence of water. A series of sulfur-containing compounds were thus obtained in high yields with good to excellent enantioselectivities. Theoretical studies indicated that the water-bridged proton transfer is a potentially favorable reaction pathway. An unprecedented O−H⋅⋅⋅π interaction between water and the aromatic nucleus of chiral phosphoric acid was discovered to contribute significantly to the stereocontrol in the catalysis. [ABSTRACT FROM AUTHOR]

A visible-light-mediated, organic photocatalytic stereoselective radical cascade cyclization of polyprenoids is described. The desired cascade cyclization products are achieved in good yields and high stereoselectivities with eosin Y as photocatalyst in hexafluoro-2-propanol. The catalyst system is also suitable for 1,3-dicarbonyl compounds, which require only catalytic amounts of LiBr to promote the formation of the corresponding enols. [ABSTRACT FROM AUTHOR]

A simple and direct α-allylic alkylation of unmodified aldehydes with allylic alcohols catalyzed by primary amine/Br⊘nsted acid has been developed. The N, N-dimethylethylenediamine/TfOH was identified as the optimal catalyst to promote this transformation via an enamine process in high yields (up to 88%) and with good diastereoselectivities (up to 9:1). [ABSTRACT FROM AUTHOR]

The chiral benzofuranone structural motif is a prominent feature in many natural products, which exhibit a broad range of biological and pharmaceutical activities. In the past few years, a survey of chiral benzofuranone derivatives based on asymmetric catalysis reveals an increasing number of papers, which reflects the latest achievements to facilitate the synthesis of sufficient quantities of related compounds as potential medicinal agents and biological probes. Recent advances in this area are summarized and classified according to the structure of the starting substrate. [ABSTRACT FROM AUTHOR]

Aromatic enamines: para‐Vinylanilines were identified as unique nucleophiles, closely resembling enamines, to undergo CC coupling with aldehydes catalyzed by a simple primary–tertiary diamine/Brønsted acid. The resulting bis(allylic) adducts, which have potential as functional materials, were obtained in high yields under rather mild conditions (see scheme). [ABSTRACT FROM AUTHOR]

A highly enantioselective catalytic double-Michael addition reaction of substituted benzofuran-2-ones with divinyl ketones promoted by readily accessible tertiary amine-thiourea Cinchona alkaloids has been developed. A number of optically enriched spirocyclic benzofuran-2-ones were prepared in very good yields (up to 99 %), diastereoselectivities (up to 19:1 d.r.), and very good enantioselectivities (up to 92 % ee). Density functional theory (DFT) calculations were performed to investigate the origin of stereoselectivity. [ABSTRACT FROM AUTHOR]

with MBH carbonates (II) leading to chiral oxindole derivatives (III) with good to high enantioselectivity and Z/E-selectivity [ABSTRACT FROM AUTHOR]

A highly enantioselective Mannich reaction of 3-substituted benzofuran-2(3 H )-ones and isatin N -Boc ketimines catalyzed by a chiral biscinchona alkaloid catalyst was developed, which proved to be an efficient way for the synthesis of chiral 3,3′-disubstituted benzofuran-2-one derivatives. The nucleophilic addition products were generally obtained in high yields (up to 99%) with very good diastereoselectivities (up to >95:5 dr) and enantioselectivities (up to 98% ee). [ABSTRACT FROM AUTHOR]

A number of popular squaramide organocatalysts’aciditieswere determined by an overlapping indicator method in DMSO via UVspectrophotometric titrations. The pKavalues are in the range of 8.37–16.46. The results may behelpful for the rational design and development of squaramide typenew catalysts. [ABSTRACT FROM AUTHOR]

A highly enantioselective sulfenylation reaction with respect to 3-substituted oxindoles and electrophilic sulfur reagents by a quinidine catalyst was investigated. [ABSTRACT FROM AUTHOR]

The 3,5-bis(trifluoromethyl)benzyl substituted compound (THU) and the analogous methyl derivative are found to be suitable catalysts for the Michael addition of 3-substituted benzofurans and alkyl 2-phthalimidoacrylates. [ABSTRACT FROM AUTHOR]

The addition of water is crucial for the stereocontrol of the title process providing sulfur containing products in high yields with moderate to high enantioselectivities. [ABSTRACT FROM AUTHOR]

The scalable reaction proceeds with high yields and excellent regio- and stereoselectivity. [ABSTRACT FROM AUTHOR]

Chiral 3,3′-disubstituted benzofuranones are synthesized from the title addition in excellent yields with very good diastereoselectivities and enantioselectivities. [ABSTRACT FROM AUTHOR]

The aerobic oxidative dehydrogenation of α-branched primary amines and cyclic secondary amines to imines without any metal cocatalyst is presented [ABSTRACT FROM AUTHOR]

Starting from 2-benzylidenebenzofuran-3-ones the synthesis of chiral dihydropyran-fused benzofurans is elaborated. [ABSTRACT FROM AUTHOR]

The article presents chemical equations for the article "Asymmetric Sulfa-Michael Addition to α-Substituted Vinyl Ketones Catalyzed by Chiral Primary Amine" by L. Zhang and others published in "Organic Letters" in 2014.

N,N-Dimethylethylenediamine·TfOH is found to be an efficient catalyst for the direct α-allylic alkylation of unmodified aldehydes with allylic alcohols. [ABSTRACT FROM AUTHOR]

The first example of the enantioselective conjugate addition of alkenes to enones, catalyzed by chiral primary amines are reported.The reaction is enabled by chiral primary amines through a typical iminium ion cycle. [ABSTRACT FROM AUTHOR]

The article presents chemical equations related to the article "Asymmetric Diels-Alder Reaction of 3-Olefinic Benzofuran-2-ones and Polyenals: Construction of Chiral Spirocyclic Benzofuran-2-ones" by X. Li and others, published in the journal "Organic Letters" in 2014.

The reactions of α-substituted vinyl aldehydes are a summary of previous results and are not shown. [ABSTRACT FROM AUTHOR]

This reaction sequence yields the spiro-products with adjacent quaternary and tertiary stereocenters with excellent enantioselectivities. [ABSTRACT FROM AUTHOR]

The regioselectivity of the formation of spiro-bis-lactones from benzofuran-2,3-diones and α,β-unsaturated β-aryl-substituted aldehydes is investigated with different N-heterocyclic carbene catalysts. [ABSTRACT FROM AUTHOR]

The reaction proceeds with moderate to high dia- and high enantioselectivities for the symmetrical and unsymmetrical diaryldienones. [ABSTRACT FROM AUTHOR]

A bifunctional Cinchona alkaloid-based organocatalyst efficiently catalyzes the asymmetric Michael addition of 3-substituted benzofuranones (I) and (IV) with bis(phenylsulfonyl)ethylene (II). [ABSTRACT FROM AUTHOR]