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A strategy for oxidative kinetic resolution of racemic indolines was developed, employing salicylaldehyde derivative as the pre-resolving reagent and chiral phosphoric acid as the catalyst. The iminium intermediate, formed by the condensation reaction of an enantiomer of indoline with salicylaldehyde derivative, was hydrogenated by the same enantiomer of indoline to afford another enantiomer of indoline by a self-redox mechanism. The oxidative kinetic resolution of 2-aryl-substituted indolines proceeded to give enantiomers in good yields with excellent enantioselectivities. [ABSTRACT FROM AUTHOR]

A strategy for oxidative kinetic resolution of racemic indolines was developed, employing salicylaldehyde derivative as the pre-resolving reagent and chiral phosphoric acid as the catalyst. The iminium intermediate, formed by the condensation reaction of an enantiomer of indoline with salicylaldehyde derivative, was hydrogenated by the same enantiomer of indoline to afford another enantiomer of indoline by a self-redox mechanism. The oxidative kinetic resolution of 2-aryl-substituted indolines proceeded to give enantiomers in good yields with excellent enantioselectivities. [ABSTRACT FROM AUTHOR]

Described herein are differences in behavior between a Hantzsch ester and a benzothiazoline as hydrogen donors in the chiral phosphoric acid catalyzed asymmetric reductive amination of ketones with p-anisidine. The asymmetric reductive amination of ketones with a Hantzsch ester as a hydrogen donor provided the corresponding chiral amines exclusively, regardless of the structures of the ketones, whereas a similar transformation with a benzothiazoline provided chiral amines and p-methoxyphenyl-protected primary amines in variable yields, depending on the structures of both the ketones and benzothiazolines. Because a benzothiazoline has an N,S-acetal moiety that is vulnerable to p-anisidine, the primary amine can be formed through transimination of the benzothiazoline with p-anisidine followed by reduction of the resulting aldimine with remaining benzothiazoline. [ABSTRACT FROM AUTHOR]

The oxidative kinetic resolution involves an asymmetric intermolecular hydride transfer from indoline to an iminium intermediate generated from indoline and the salicylaldehyde reagent. [ABSTRACT FROM AUTHOR]

Attempted asymmetric reductive amination of benzyl methyl ketones with benzothiazoles (II) as hydrogen donor does not give any yields of the expected β-arylamine whereas phenyl methyl ketone gives the reductive amination product (VII) with moderate e.e. [ABSTRACT FROM AUTHOR]

The article presents chemical equations related to the article "Phosphoric Acid Bridged Cobalt Bis(dicarbollide) Ion as a Highly Efficient Catalyst for the Organocatalytic Hydrogenation of Ketimines" by T. Akiyama and others, published in the journal "Synlett" in 2014.

Reported herein is an enantiodivergent synthesis of chiral biaryls by a chiral phosphoric acid catalyzed asymmetric transfer hydrogenation reaction. Upon treatment of biaryl lactols with aromatic amines and a Hantzsch ester in the presence of chiral phosphoric acid, dynamic kinetic resolution (DKR) involving a reductive amination reaction proceeded smoothly to furnish both R and S isomers of chiral biaryls with excellent enantioselectivities by proper choice of hydroxyaniline derivative. This trend was observed in wide variety of substrates, and various chiral biphenyl and phenyl naphthyl adducts were synthesized with satisfactory enantioselectivities in enantiodivergent fashion. The enantiodivergent synthesis of synthetically challenging, chiral o-tetrasubstituted biaryls were also accomplished, and suggests high synthetic potential of the present method. [ABSTRACT FROM AUTHOR]

Reported herein is an enantiodivergent synthesis of chiral biaryls by a chiral phosphoric acid catalyzed asymmetric transfer hydrogenation reaction. Upon treatment of biaryl lactols with aromatic amines and a Hantzsch ester in the presence of chiral phosphoric acid, dynamic kinetic resolution (DKR) involving a reductive amination reaction proceeded smoothly to furnish both R and S isomers of chiral biaryls with excellent enantioselectivities by proper choice of hydroxyaniline derivative. This trend was observed in wide variety of substrates, and various chiral biphenyl and phenyl naphthyl adducts were synthesized with satisfactory enantioselectivities in enantiodivergent fashion. The enantiodivergent synthesis of synthetically challenging, chiral o-tetrasubstituted biaryls were also accomplished, and suggests high synthetic potential of the present method. [ABSTRACT FROM AUTHOR]

A chiral Brønsted acid catalyzed dehydrogenative kinetic resolution of tetrahydroquinoline derivatives, which are representative of cyclic secondary amines, based on their hydrogen transfer to aromatic imines was efficiently achieved with high enantioselectivities. This hydrogen transfer of tetrahydroquinolines to imines was not driven by their aromatization to quinolines. This dehydrogenative kinetic resolution could be also applied to the asymmetric synthesis of various benzofused heterocycles containing secondary amine cores. [ABSTRACT FROM AUTHOR]

Described herein is a highly enantioselective synthesis of fused piperidine and pyrrolidine derivatives with all-carbon stereogenic centers. The enantioselective reductive amination from Cs-symmetric 1,3-dione derivatives proceeded in a highly stereoselective manner by taking advantage of the desymmetrization approach to afford fused heterocycles with contiguous stereogenic centers in good to excellent enantioselectivities (up to 98% ee). [ABSTRACT FROM AUTHOR]

The Friedel‐Crafts alkylation reaction of 4,7‐dihydroindole with N‐unprotected trifluoromethyl ketimines by means of chiral phosphoric acid and the subsequent oxidation with DDQ afforded chiral 2‐indolylmethylamines bearing a trifluoromethyl moiety in good to high yields with excellent enantioselectivities under one‐pot conditions. The adduct was transformed without loss of enantioselectivity and the absolute stereochemistry was determined by X‐ray crystallographic analysis. [ABSTRACT FROM AUTHOR]

A new approach is described for the asymmetric synthesis of 1-substituted 1,2,3,4-tetrahydroisoquinolines that is based on the enantioselective 1,3-dipolar cycloaddition reaction of a nitrone and a vinyl ether in the presence of a chiral phosphoric acid that gives the chiral tetrahydroisoquinolines in high yields and with high enantioselectivities.1 H and31 P NMR analyses of the mixture of nitrone and chiral phosphoric acid suggest the formation of a 1:1 complex. [ABSTRACT FROM AUTHOR]

An enantioselective Friedel–Crafts alkylation reaction of pyrroles and indoles with N‐unprotected trifluoromethyl ketimines by use of chiral phosphoric acid provided α‐trifluoromethylated primary amines bearing chiral tetrasubstituted carbon centers in high yields and with high to excellent enantioselectivities. The present reaction is unique to N‐unprotected trifluoromethyl ketimines. No reaction took place with N‐p‐methoxyphenyl (PMP)‐substituted ketimine. Corresponding α‐trifluoromethylated amines were transformed without loss of enantioselectivity. [ABSTRACT FROM AUTHOR]

Abstract: 1,3‐Dipolar cycloadditions (1,3‐DC) between imino esters (as precursors of N‐metallated azomethine ylides) and π‐deficient alkenes are promoted by cooperative asymmetric Lewis acid/Brønsted base catalysis. The components of these catalytic pairs are silver salts derived from enantiopure commercially available BINOL‐based phosphoric acids and Cinchona alkaloids. Chiral phosphoric silver(I) salts promote HOMO raising of in situ formed 1,3‐dipoles, whereas protonated cinchona alkaloids generate a LUMO lowering for the dipolarophiles resulting in a global acceleration of the 1,3‐DC. The best results were obtained with BINOL‐derived silver phosphate and hydrocinchonine. Matching between both cooperative metallo‐ and organocatalyst results in an enhanced enantiomeric excess, superior to that reached by both separate components. NOESY experiments and DFT calculations are compatible with a non‐covalent interaction (hydrogen bond) between both catalysts, which results in close contacts and mutually coupled chiral environments. [ABSTRACT FROM AUTHOR]

An abstract of the article "Chiral Phosphoric Acid Catalyzed Oxidative Kinetic Resolution of Cyclic Secondary Amine Derivatives Including Tetrahydroquinolines by Hydrogen Transfer to Imines" by K. Saito and colleagues is presented.

An abstract of the article "Enantioselective Synthesis of Fused Heterocycles with Contiguous Stereogenic Centers by Chiral Phosphoric Acid Catalyzed Symmetry Breaking" by Keiji Mori, Ayaka Miyake and Takahiko Akiyama is presented.

Asymmetric synthesis of tetrahydrobenzodiazepines was achieved by transfer hydrogenation of dihydrobenzodiazepines with benzothiazoline having a hydrogen-bonding donor substituent by means of a newly synthesized chiral phosphoric acid. This method was applicable to various racemic dihydrobenzodiazepines to give the corresponding products in good yields with excellent diastereoselectivities and enantioselectivities taking advantage of the dynamic kinetic resolution. Furthermore, the effect of bulky substituent at 3,3′-position on the catalyst and hydrogen-bonding donor substituent on benzothiazoline was fully elucidated by the theoretical study. [ABSTRACT FROM AUTHOR]

Friedel-Crafts alkylation of indoles by (Z)-nitroalkenes proceeds highly enantioselective in the presence of chiral phosphoric acid. [ABSTRACT FROM AUTHOR]

We report herein a highly enantioselective synthesis of multisubstituted biaryl chlorides/iodides by sequential halogenation reactions (desymmetrization/kinetic resolution sequence). The selectivity of biaryl chlorides/iodides obtained in the first asymmetric reaction (desymmetrization) could be enhanced by the kinetic resolution-type asymmetric bromination to afford the corresponding chiral biaryl chlorides/iodides in excellent selectivities (up to 99 % ee). [ABSTRACT FROM AUTHOR]

Dihydrobenzodiazepines or benzodiazepines bearing aryl substituents at the 2- and 4-position of the heterocyclic part are transformed to the chiral title compounds in the presence of BNPA using different amounts of the hydrogen transfer reagent BTA. [ABSTRACT FROM AUTHOR]

Chiral biaryl halogenides [(II) and (IV)] are synthesized with high enantioselectivities by chiral phosphoric acid catalyzed asymmetric iodination or chlorination followed by kinetic resolution-type asymmetric bromination. [ABSTRACT FROM AUTHOR]

It is demonstrated that asymmetric hydrogenation of ketimines can be advantageously achieved with benzothiazoline as hydrogen donor in the presence of a chiral BINOL derived phosphonic acid as catalyst. [ABSTRACT FROM AUTHOR]