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Abstract: Direct trifluoromethylation of 1,3-dicarbonyl compounds with CF3I in the presence of a Fenton reagent in dimethylsulfoxide was investigated. 1,3-Diketones, 3-oxocarboxylates and 3-oxocarboxamides were readily trifluoromethylated at the methylene carbon between two oxo groups. Cycloaddition of hydrazine derivatives to the obtained 2-(trifluoromethyl)-1,3-dicarbonyl compounds provided fluorinated pyrazoles. 4-(Trifluoromethyl)pyrazole derivatives were formed from 2-(trifluoromethyl)-1,3-diketones, while 3-oxo-2-(trifluoromethyl)carboxylates or carboxamides gave 5-fluoropyrazole-4-carboxylates or carboxamides, respectively, via 3-hydrazono-2-(trifluoromethyl)carboxylates or carboxamides as an intermediate. [Copyright &y& Elsevier]

Abstract: The catalytic trifluoromethylation of uracil using CF3I was investigated to find a new industrial process for the production of 5-trifluoromethyluracil. The catalytic system of FeSO4, H2O2 and H2SO4 in dimethylsulfoxide efficiently and selectively yielded 5-trifluoromethyluracil under mild conditions. FeSO4 exhibited the highest activity among the Fe(II) compounds tested. H2O2 was indispensable for the reaction and only Fe(II) compounds yielded the desired product. This characteristic of the reaction suggests that it proceeds in a Fenton oxidation manner. The reaction was applicable to large-scale production: 50kg of 5-trifluoromethyluracil in a 600L reactor. By the use of this catalytic system, selective trifluoromethylation at the 5-position was also performed with various uracil derivatives including uridines. Interestingly, Cp2Fe was superior to FeSO4 for several substrates. [Copyright &y& Elsevier]

Highly enantioselective alkylation of azlactones derived from α-amino acids has been achieved under solid-liquid phase-transfer conditions using P-spiro chiral tetraaminophosphonium salt as a catalyst. The resulting alkylated azlactones can be readily converted into the corresponding α,α-disubstituted α-amino acids through simple acidic hydrolysis. [ABSTRACT FROM AUTHOR]

The parasitic plant Striga hermonthica has been causing devastating damage to the crop production in Africa. Because Striga requires host-generated strigolactones to germinate, the identification of selective and potent strigolactone agonists could help control these noxious weeds. We developed a selective agonist, sphynolactone-7, a hybrid molecule originated from chemical screening, that contains two functional modules derived from a synthetic scaffold and a core component of strigolactones. Cooperative action of these modules in the activation of a high-affinity strigolactone receptor ShHTL7 allows sphynolactone-7 to provoke Striga germination with potency in the femtomolar range. We demonstrate that sphynolactone-7 is effective for reducing Striga parasitism without impinging on host strigolactone-related processes [ABSTRACT FROM AUTHOR]

Scavengers that capture reactive chemical substances are used to prevent the decomposition of materials. However, in the field of catalysis, the development of scavengers that inhibit background pathways has attracted little attention, although the concept will open up an otherwise inaccessible reaction space. In catalytic bromination, fast non‐catalyzed background reactions disturb the catalytic control of the selectivity, even when using N‐bromoamide reagents, which have a milder reactivity than bromine (Br2). Here, we developed a trans‐cyclooctene (TCO) bearing a 2‐pyridylethyl group to efficiently retard background reactions by capturing Br2 in bromocyclization using N‐bromosuccinimide. The use of less than a stoichiometric amount of the TCO was sufficient to inhibit non‐catalyzed reactions, and mechanistic studies using the TCO revealed that in situ‐generated Br2 provides non‐catalyzed reaction pathways based on a chain mechanism. The TCO is useful as an additive for improving enantioselectivity and regioselectivity in catalytic reactions. Cooperative systems using the TCO with selective catalysts offer an alternative strategy for optimizing catalyst‐controlled selectivity during bromination. Moreover, it also served as an indicator of Br2 involved in catalytic reaction pathways; thus, the TCO was useful as a probe for mechanistic investigations into the involvement of Br2 in bromination reactions of interest. [ABSTRACT FROM AUTHOR]

A divergent photocatalytic system for the reaction of α-bromo nitroalkanes with styrene derivatives is established, wherein the generation of the persistent nitroxyl radical as a junctional intermediate and suitable tuning of the redox ability of the system constitute the crucial elements for achieving rigorous control over the possible reaction pathways. [ABSTRACT FROM AUTHOR]

Catalytic systems that allow selective generation of any diastereomer of a reaction product bearing multiple stereocentres through minimal modification of a single catalyst scaffold remain elusive, particularly for carbon-carbon bond formations requiring simultaneous control of multiple selectivity factors. Here, we report a catalyst-directed pinpoint inversion of diastereochemical preference in the 1,6-addition of azlactones to δ-aryl dienyl carbonyl compounds with full control over other selectivities preserved. This rigorous diastereodivergence is enabled by the slight structural adjustment of a chiral iminophosphorane catalyst, providing access to all the stereoisomers with high regio-, distereo- and enantioselectivity. The utility of this method is demonstrated in the facile stereodivergent preparation of densely functionalized proline derivatives. The experimental and computational elucidation of the origin of the diastereodivergence is also reported. [ABSTRACT FROM AUTHOR]

Abstract: The catalytic performance of C 1-symmetric chiral ammonium betaines in the enantioselective direct Mannich-type reaction of α-nitrocarboxylates with N-Boc imines has been investigated. The most effective catalyst structure has been identified; this provides a reliable synthetic route to a variety of enantiomerically enriched α-tetrasubstituted α,β-diamino acid derivatives. [ABSTRACT FROM AUTHOR]

Trifluoromethylation followed by acid hydrolysis furnishes compounds (III) which can be converted to (2,2,2-trifluoroethyl)ketones via decarboxylation. [ABSTRACT FROM AUTHOR]

An abstract of the article "Synergistic Catalysis of Ionic Broensted Acid and Photosensitizer for a Redox Neutral Asymmetric alpha-Coupling of N-Arylaminomethanes with Aldimines" by D. Uraguchi, N. Kinoshita and T. Kizu is presented.

The article reports a study which uncovers a new function of chiral tetraaminophosphonium cations and its potential synthetic utility. According to the study, the heterochiral [7.7]-P-spirocyclic arylaminophosphonium barfates have been designed as a novel charged and cationic Brønsted acid catalyst. The study shows new functions of chiral aminophosphonium cations and that potential utility of asymmetric hydrogen-bonding catalysis is currently under close investigation.

The article offers information on chiral phosphonium dialkyl phosphite generation as chemical reagents. It notes that diakyl phosphonates are used for the asymmetric construction of phosphorus-carbon (P-C) bond in synthesizing chiral phosphonic acid derivatives. The relation of dialkyl phosphonates as P-nucleophile is affected by the concept of the phosphite tautomer. It also notes the creation of asymmetric catalysts of a chiral organic base for hydrophosphonylation of aldehydes.

Various substituted aryl groups for both imines (I) and nitromethanes (II) are tolerated in the reaction. [ABSTRACT FROM AUTHOR]

Using a chiral iminophosphorane catalyst, the Michael addition between β-substituted alkynyl N-acyl pyrazoles and 2-benzyloxythiazol-5(4H)-ones proceeds with high yields and excellent stereo- and E/Z-selectivities. [ABSTRACT FROM AUTHOR]

The article presents a study which examines the asymmetric catalysis of chiral tetraaminophosphonium carboxylate. Its synthetic utility has been demonstrated by the application to the highly enantioselective direct Mannich-type reaction of azlactones with N-sulfonyl imines. The procedures employed in the experiment, as well as the observations and results of the study are also discussed,

The article discusses a study on the chiral tetraaminophosphonium salt-mediated asymmetric direct Henry reaction. The study employed a chiral tetraaminophosphonium salt possessing the P-spirocyclic structure and its potential as an organic molecular catalyst. The development and application of a chiral tetraaminophosphonium chloride demonstrating its inherent potential to exert efficient asymetric catalysis. Researchers believe that this study offers a new axis of chiral onium salt catalyses.

This article focuses on organocatalytic asymmetric direct alkylation of α-diazoester via carbon-hydrogen bond cleavage. It has attracted much attention from industry as well as the academic community due to its atom efficiency. In conjunction with the recent efforts to develop chiral acids for catalyzed asymmetric carbon-carbon bond forming reactions, researchers recently demonstrated a highly enantio selective 1,2-aza-F-C reaction of a furan derivative to N-protected aldimines catalyzed by chiral phosphoric acid.

The article reports on the highly enantioselective 1,2-aza-Friedel-Crafts reaction catalyzed by a binaphthol mono-phosphoric acid. In view of the significance of controlling the stereochemistry in an absolute sense, the successful cultivation of a catalytic enantioselective variant of this reaction is in high demand. Since optically active furan-2-ylamines are highly useful synthetic building blocks, the article states the development of an enantioselective 1 ,2-aza-F-C reaction of a furan with N-Boc aldimine derivatives.

This article presents a study on the chiral Brønsted acid-catalyzation through direct Mannich reactions via electrophilic activation. It is a well-accepted that nearly a "proton"-like character is required for activating a substrate efficiently and hence chiral Brønsted acids could not provide a chiral environment to a reactive intermediate. Researchers have developed highly enantioselective Strecker reactions and Mannich reactions catalyzed by peptide-based thiourea derivatives as chiral Brønsted acids. Their achievement has clearly indicated that a chiral Brønsted acid could recognize enantiotopic faces of an imine substrate via hydrogen bonding and has opened up a new avenue in asymmetric catalysis.

The relief of the steric repulsion between cis-oriented substituents of the nitroolefins seems to assist the facile generation of the vinylogous nitronates, which react with N-Boc aldimines at the sterically more congested α-position exclusively, thus establishing the contiguous tertiary-quaternary stereocenters. [ABSTRACT FROM AUTHOR]

The article presents a chemical reaction of protonation of carboxylic acid-derived ketone by using the chiral ionic broensted acid catalysis.

A novel class of chiral N-sulfonyl oxaziridines is introduced for use as structurally modifiable chiral oxidants. These oxaziridines are readily prepared from N-sulfonyl α-imino esters in a highly enantioenriched form by oxidation with hydrogen peroxide using l-isoleucine-derived triaminoiminophosphorane as a catalyst. The distinct advantage of their structural modularity is demonstrated through the identification of an optimal oxaziridine that exhibits high reactivity and enantiospecificity in the asymmetric oxidation of a silyl enol ether and N-sulfonyl allylic and homoallylic amines. [ABSTRACT FROM AUTHOR]

A highly regio-, diastereo-, and enantioselective 1,6-addition of azlactone to various alkenyl dienyl ketones has been achieved under P-spiro chiral triaminoiminophosphorane catalysis. This site-selectivity control relies on the distinct ability of the conjugate acids of iminophosphoranes, aminophosphonium ions, to precisely differentiate between the three electrophilic reaction sites of alkenyl dienyl ketones, which is further demonstrated by the discriminative asymmetric 1,6-addition of azlactone to dienyl ketones, leaving the coexisting alkenyl ketone intact. [ABSTRACT FROM AUTHOR]