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A Lewis acid-mediated decarboxylative 1,2-rearrangement reaction of cyclic carbonates was developed. The selectivity of the migration in the decarboxylative 1,2-rearrangement of cyclic carbonates was opposite to that of the corresponding 1,2-diols under the same reaction conditions. This contrasting selectivity of the migration was confirmed in a variety of substrates. [ABSTRACT FROM AUTHOR]

The stereoselective synthesis of aminovinyloxazolidinones based on the electrophilic amination of a vinyl-silver intermediate, generated by silver-catalyzed carbon dioxide incorporation on a propargyl amine, was achieved. The geometry of the aminated product was determined by a single crystal X-ray analysis and NOE measurement and it was elucidated that the geometry was proved to be opposite to the geometry predicted from the previous silver-catalyzed carbon dioxide fixation on a propargyl amine derivative. This unexpected stereoselectivity could be successfully explained by a radical mechanism. [ABSTRACT FROM AUTHOR]

The present study describes the cationic oxo‐thiolation of polymerizable alkenes by using highly reactive cationic species generated by anodic oxidation. These highly reactive cations were able to activate alkenes before their polymerization. Fast mixing in flow microreactors effectively controlled chemoselectivity, enabling higher reaction temperatures. [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]

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]

The titanium tetrachloride-catalyzed hydrodefluorination reaction of trifluorotoluene derivatives was developed using triethylsilane as the reducing agent. The reaction produced various toluene derivatives with high chemoselectivities by means of readily accessible reagents. This hydrodefluorination process was extended to the intramolecular Friedel-Crafts benzylation reaction, furnishing polycyclic aromatics of various ring sizes in good yields. [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]

The asymmetricreduction of ketimines is animportant method for the preparation of amines in optically pure form.Inspired by the biological system using NAD(P)H, Hantzsch ester hasbeen extensively employed as a hydrogen donor in combination withchiral phosphoric acid for the transfer hydrogenation of ketiminesto furnish amines with high to excellent enantioselectivities. [ABSTRACT FROM AUTHOR]

The chiral phosphoricacid catalyzed enantioselective transferhydrogenation of various ketimines was achieved by the use of 2-arylindoline as the hydrogen donor. Corresponding chiral amines were obtainedin good chemical yields with excellent enantioselectivities. [ABSTRACT FROM AUTHOR]

Chiral phosphoric acid catalyzed transfer hydrogenation of ketimines derived from propiophenone derivatives and reductive amination of alkyl ethyl ketone derivatives were extensively examined in the presence of two representative hydrogen donors. The excellent enantioselective transfer hydrogenation was achieved by use of benzothiazoline as a hydrogen donor. The theoretical studies elucidated that the unsymmetrical structure of benzothiazoline plays an important role in high enantioselective hydrogenation. [ABSTRACT FROM AUTHOR]

The high-yield reduction of aromatic ketimines into amines by using a novel catalyst based on a metallacarborane structure, 8,8'-μ-phosphate[(1,2-dicarba-closo-undecaborane)-3,3'-cobalt(- 1)(1',2'-dicarba-closo-undecaborane)] acid, is described. [ABSTRACT FROM AUTHOR]

In the Twitter blogosphere, the number of followers is probably the most basic and succinct quantity for measuring popularity of users. However, the number of followers can be manipulated in various ways; we can even buy follows. Therefore, alternative popularity measures for Twitter users on the basis of, for example, users' tweets and retweets, have been developed. In the present work, we take a purely network approach to this fundamental question. First, we find that two relatively distinct types of users possessing a large number of followers exist, in particular for Japanese, Russian, and Korean users among the seven language groups that we examined. A first type of user follows a small number of other users. A second type of user follows approximately the same number of other users as the number of follows that the user receives. Then, we compare local (i.e., egocentric) followership networks around the two types of users with many followers. We show that the second type, which is presumably uninfluential users despite its large number of followers, is characterized by high link reciprocity, a large number of friends (i.e., those whom a user follows) for the followers, followers' high link reciprocity, large clustering coefficient, large fraction of the second type of users among the followers, and a small PageRank. Our network-based results support that the number of followers used alone is a misleading measure of user's popularity. We propose that the number of friends, which is simple to measure, also helps us to assess the popularity of Twitter users. [ABSTRACT FROM AUTHOR]

A good mix: The title reaction of o‐alkynylacetophenones with the Hantzsch ester in the presence of a chiral copper/phosphate catalyst proceeds in good yields with excellent enantioselectivities. The key intermediate for enantiocontrol is the ion pair of the carbonyl ylide with a chiral phosphate anion, and this process provides straight forward access to highly enantioriched chiral isochromenes. [ABSTRACT FROM AUTHOR]

Gute Mischung: o ‐ Alkinylacetophenone werden in der Titelreaktion mit dem Hantzsch ‐ Ester in guten Ausbeuten erhalten. Das entscheidende Intermediat für die Enantioselektivität ist ein Ionenpaar aus dem Carbonyl ‐ Ylid und einem chiralen Phosphatanion. Der Prozess führt direkt zu hoch enantiomerenangereicherten chiralen Isochromenen. [ABSTRACT FROM AUTHOR]

Abstract: Development of a novel method for generating glycosyl cations or their equivalents is highly desired, because such intermediates are crucial for developing stereoselective glycosylations in oligosaccharide syntheses. In this review we focus on electrochemical methods that we have recently developed. The anodic oxidation of thioglycosides is effective for generating glycosyl triflate pools, which react with glycosyl acceptors. The reaction of glycosyl triflate pools with diorganosulfides gives glycosyl sulfonium ions, which also serve as effective glycosylation intermediates. The indirect electrochemical method is effective for the generation of glycosyl cations or their equivalents and the use of a flow-microreactor system enables glycosylation using such intermediates. [Copyright &y& Elsevier]

Pt(H)-catalyzed generation of unsaturated carbene complex intermediates from various propargyl ether derivatives based on electrophiic activation of alkynes was realized. These in situ generated unsaturated carbene complexes undergo [3+2] cycloaddition reaction with various vinyl ethers, leading to efficient formation of indoles, naphthols, and benzofuran fused with a five-membered ring in high yields. [ABSTRACT FROM AUTHOR]

Cover Feature: Oxo-Thiolation of Cationically Polymerizable Alkenes Using Flow Microreactors (Chem. Eur. J. 67/2019) Keywords: alkenes; anodic oxidation; cationics; electrochemistry; flow microreactors; polymerization Alkenes, anodic oxidation, cationics, electrochemistry, flow microreactors, polymerization. [Extracted from the article]

A homoallylic ketone can be transformed and functionalized by various synthetic reactions, and thus, is regarded as one of the representative building blocks in organic chemistry. An additional route to access homoallylic ketones, namely, a Lewis acid‐mediated decarboxylative allylation of cyclic enol carbonates, prepared by fixation of carbon dioxide onto propargyl alcohols, was developed in this work. The treatment of a cyclic enol carbonate with a Lewis acid in the presence of an allylsilane resulted in the formation of a homoallylic ketone. It was found that the title reaction proceeded well by the combined use of zirconium tetrachloride with allyltrimethylsilane. The allylation occurred with high regioselectivity and the corresponding homoallylic ketones were obtained in good‐to‐high yields. A reaction mechanism involving the decarboxylative formation of an oxyallyl cation equivalent is proposed. [ABSTRACT FROM AUTHOR]

Decarboxylative homo-Nazarov cyclization catalyzed by a Lewis acid was achieved using a cyclic enol carbonate bearing a cyclopropane moiety as a substrate. Various substrates were converted into the corresponding multi-substituted cyclohexenones in good yields via decarboxylation, followed by 6-membered ring formation involving cyclopropane-ring-opening. [ABSTRACT FROM AUTHOR]

The combined use of an organic base for resorcinols realized a Kolbe–Schmitt type reaction under ambient conditions. When resorcinols (3-hydroxyphenol derivatives) were treated with DBU under a carbon dioxide atmosphere, nucleophilic addition to carbon dioxide proceeded to afford the corresponding salicylic acid derivatives in high yields. [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]

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 "Chiral Phosphoric Acid Catalyzed Asymmetric Synthesis of 2-Substituted 2,3-Dihydro-4-quinolones by a Protecting-Group-Free Approach" by K. Saito and colleagues is presented.

The method is highly chemoselective and applied to the reduction of a wide range of sulfides, including benzyl and alkyl sulfides, and dithianes. [ABSTRACT FROM AUTHOR]

Review: 62 refs. [ABSTRACT FROM AUTHOR]

The article presents chemical equations related to the article "Asymmetric Transfer Hydrogenation of Ketimines by Indoline as Recyclable Hydrogen Donor" by K. Saito and colleagues, published in the "ChemInform" journal in 2014.

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]

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.

The article presents chemical equations related to chiral copper (II) phosphate catalyzed enantioselective synthesis of isochromene derivatives of o-Alkynylacetophenones by K. Saito and others, published in the "Angewandte Chemie International Edition" in 2013.

This new method proceeding via hydrogen transfer to imines by means of a chiral phosphoric acid catalyst is applicable to both 2-aryl and 2-alkyl substituted indolines. [ABSTRACT FROM AUTHOR]

Review: 59 refs. [ABSTRACT FROM AUTHOR]

A highly enantioselective protocol for the reductive amination of aliphatic ketones with aromatic amines catalyzed by a chiral phosphoric acid is presented. [ABSTRACT FROM AUTHOR]

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]

The use of functionalised allylboronic esters in the catalytic enantioselective allylboration of aldehydes is described for the first time. γ-Silylallyl pinacolate derivatives give rise to α-silyl homoallylic alcohols in high yields, with complete diastereoselectivities and high enantioselectivities, in most of the cases. The usefulness of such intermediates is showcased by their transformation into fluorinated allylic alcohols. [ABSTRACT FROM AUTHOR]

Platinum(II)-catalyzed intermolecular formal [4+3]-cycloaddition reaction of α,β-unsaturated carbene complex intermediates with siloxydienes proceeded under mild conditions to give cyclohepta[b]indole derivatives in good yield. The reaction was found to proceed via 1,2-alkyl shift of the carbene complex intermediates obtained by [4+2]-cycloaddition reaction of the unsaturated carbenes with dienes. [ABSTRACT FROM AUTHOR]

Highly substituted 2-cyclopentenones were stereospecifically and regioselectively constructed with high catalytic efficiency through Lewis-acid catalyzed decarboxylative Nazarov cyclization of the cyclic carbonate derivative, which is prepared by reacting the propargyl alcohol with carbon dioxide in the presence of a silver catalyst. The stereochemistry of the 2-cyclopentenone is strictly controlled by the geometry of the alkene in the starting material. This method is applicable for various substrates. [ABSTRACT FROM AUTHOR]

Highly substituted 2-cyclopentenones were stereospecifically and regioselectively constructed with high catalytic efficiency through Lewis-acid catalyzed decarboxylative Nazarov cyclization of the cyclic carbonate derivative, which is prepared by reacting the propargyl alcohol with carbon dioxide in the presence of a silver catalyst. The stereochemistry of the 2-cyclopentenone is strictly controlled by the geometry of the alkene in the starting material. This method is applicable for various substrates. [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]

Functionalized allylboronic esters are used for the catalytic enantioselective allylboration of various aldehydes affording α-silyl homoallylic alcohols with complete diastereoselectivities and high enantioselectivities in most cases. [ABSTRACT FROM AUTHOR]

The article presents chemical equations on the article "Enantioselective Transfer Hydrogenation of Difluoromethyl Ketimines Using Benzothiazoline as a Hydrogen Donor in Combination with a Chiral Phosphoric Acid" by T. Sakamoto and others, published in the "Journal of Organic Chemistry."

This unique reaction allows the synthesis of the title compounds under mild reaction conditions. [ABSTRACT FROM AUTHOR]