Halogen bonding accelerated aerobic dehydrogenative aromatization for 4-aminoquinoline preparation.

This study presents a highly efficient method for 4-aminoquinoline derivative preparation under transition metal-free conditions. The process involves an aerobic oxidative dehydrative coupling of 2,3-dihydroquinolin-4(1)-ones with various amines, including ammonia, resulting in high yields of the desired products. The method is also applicable to substituted 4-aminoquinoline derivative construction through a cyclization/dehydrative coupling cascade process starting from 2'-amino chalcones.

Rh(III)-Catalyzed C7-Alkylation of Isatogens with Malonic Acid Diazoesters.

Rh(III)-catalyzed C7-alkylation of isatogens (indolin-3-one -oxides) with malonic acid diazoesters has been developed. This strategy utilizes oxygen anion on the -oxide group of isatogens as a directing group and successfully achieves the synthesis of a series of C7-alkylated isatogens with moderate to good yields (48-86% yields). Moreover, the -oxides of isatogens can not only serve as the simple directing group for C7-H bond cleavage but also be deoxidized for easy removal.

Aerobic Dehydrogenative Aromatization in the Preparation of 4-Aminoquinoline Derivatives by Synergistic Pd/Cu Catalysis.

The 4-aminoquinoline moiety is widely present in various bioactive compounds and marketed drugs, while the preparation of this target structure relies heavily on the amination of 4-chloroquinolines. Herein, an atom and step economic procedure was developed based on an aerobic dehydrogenative aromatization strategy. Unlike the well-known palladium-catalyzed dehydrogenative aromatization of cyclohexanones with amines, synergistic Pd/Cu catalysis is crucial for 2,3-dihydroquinolin-4(1)-one type of substrates.

A New Fluorescent Probe for Hydrogen Sulfide Detection in Solution and Living Cells.

Since Hydrogen Sulfide (HS) was recognized as a gas transmitter, its detection and quantification have become a hot research topic among chemists and biologists. In this area, fluorescent probes have shown great advantages: fast and strong response, low detection limit and easy manipulation. Here we developed a new fluorescent probe that detected HS selectively among various bioactive and inorganic salts.

Synthesis of -Unsubstituted and 3-Substituted Quinazoline-2,4(1,3)-diones from -Aminobenzamides and CO at Atmospheric Pressure and Room Temperature.

The unprecedented metal-free synthesis of both -unsubstituted and 3-substituted quinazoline-2,4(1,3)-diones from -aminobenzamides and CO under atmospheric pressure at room temperature is developed. This protocol easily allows for variations of functional groups (including alkyl, aryl, and heterocycle groups) at the 3-position to accommodate the construction of many important drugs and bioactive compounds. The reaction features eco-friendliness, substrate scope tolerance, and versatility and can be implemented even at the gram scale.

Protecting-Group-Free Synthesis of Meridianin A-G and Derivatives and Its Antibiofilm Evaluation.

Herein, a protecting-group-free protocol was developed to realize a time and step economy diversification of the Meridianin alkaloid. A broad range of substituents are tolerated to deliver the products in moderate to high yields, and the first synthesis of Meridianin B was achieved. The simplicity of this protocol enables the rapid construction of a Meridianin derivative library for antibiofilm evaluation.

DBU-Catalyzed Aerobic CDC Reaction of Thiophenols.

A convenient method was developed for the preparation of thiolated compounds a DBU-catalyzed aerobic cross-dehydrogenative coupling (CDC) reaction. The established protocol is environmentally friendly and operationally simple. Substrates like (hetero)aryl acetates, (hetero)aryl ketones, and indoles could be transformed into the corresponding thiolated products in moderate to high yields and further applied in the preparation of bioactive compounds in a prefunctionalization-free manner.

Synthesis and antibiofilm evaluation of N-acyl-2-aminopyrimidine derivatives against Acinetobacter baumannii.

The overuse of antibiotics will led to the increase of drug resistance. Especially, the multidrug-resistant A. baumannii became the leading cause of nosocomial infections with high rates of morbimortality.

Synthesis and antibacterial activity studies of indirubin-3'-monoximes.

Multi-drug-resistant microbial pathogens are a serious global health problem. New compounds with antibacterial activity serve as good candidates for developing novel antibacterial drugs which is very urgent and important. In this work, based on the unique scaffold of indirubin, an active ingredient of traditional Chinese medicine formulation Danggui Luhui Wan, we synthesized 29 indirubin-3'-monoximes and preliminarily evaluated their antibacterial activities.

Cobalt-promoted synthesis of sulfurated oxindoles radical annulation of -arylacrylamides with disulfides.

An efficient radical annulation of -arylacrylamides with disulfides is developed for the synthesis of sulfurated oxindoles. The reaction occurs in a facile manner using CoBr as both an initiator and a promoter for the first time and (NH)SO as the oxidant. By controlling the CoBr/(NH)SO ratio, a wide range of sulfurated and brominated/sulfurated oxindoles are selectively prepared in good to excellent yields.

Cinchona-Alkaloid-Derived NNP Ligand for Iridium-Catalyzed Asymmetric Hydrogenation of Ketones.

Most ligands applied for asymmetric hydrogenation are synthesized via multistep reactions with expensive chemical reagents. Herein, a series of novel and easily accessed cinchona-alkaloid-based NNP ligands have been developed in two steps. By combining [Ir(COD)Cl], 39 ketones including aromatic, heteroaryl, and alkyl ketones have been hydrogenated, all affording valuable chiral alcohols with 96.

Iron-Catalyzed Radical Annulation of Unsaturated Carboxylic Acids with Disulfides for the Synthesis of γ-Lactones.

An efficient aerobic iron-catalyzed annulation of unsaturated carboxylic acids with disulfides has been developed. This procedure proceeds using FeCl as the catalyst and KI as an iodine source under an air atmosphere, which provides practical access to a wide range of substituted γ-lactone derivatives. The disclosed method is quite simple, highly atom-economic, environmentally friendly, and tolerates a broad substrate scope.

Enantioselective amination of 4-alkylisoquinoline-1,3(2,4)-dione derivatives.

A mild and efficient enantioselective amination of 4-alkylisoquinoline-1,3(2,4)-dione derivatives was established, which is compatible with a broad range of substrates and delivers the final products in excellent yields (up to 99%) and ee values (up to 99%) with low catalyst loading (down to 1 mol%). The synthetic potential of this methodology was also demonstrated in the gram scale level.

Palladium catalyzed asymmetric allylic alkylation of isoquinolinedione derivatives in the preparation of quaternary carbon stereocenters.

A highly enantioselective allylic alkylation of isoquinolinedione derivatives under palladium catalysis was developed in the preparation of quaternary carbon stereocenters. Under standard reaction conditions, excellent yields and enantioselectivities were realized and the products could be transformed into dihydroisoquinolone with vicinal chiral carbon centers or THIQ core structures in short steps with high yields.

Organocatalytic Asymmetric α-Sulfenylation of 2-Substituted Indolin-3-ones: A Strategy for the Synthesis of Chiral 2,2-Disubstituted Indole-3-ones with S- and N-Containing Heteroquaternary Carbon Stereocenter.

An organocatalytic asymmetric α-sulfenylation of 2-substituted indolin-3-ones with N-(alkylthio or arylthio)succinimides has been developed for the first time using Cinchona-derived squaramide as the catalyst. Various chiral 2,2-disubstituted indole-3-ones with S- and N-containing heteroquaternary carbon stereocenters were obtained with up to 98% yield and 99% ee.

Catalyst-free Cleavage of Amide and C-O Double Bond for the Diastereoselective Synthesis of Trifluoromethyl-Containing Dihydrooxazole Derivatives.

A novel and efficient cascade method has been developed for the diastereoselective preparation of trifluoromethyl-containing dihydrooxazoles in high yields. The reaction was applicable to electron-deficient, electron-rich arenes, heteroarenes, and alkyl groups. Control experiments were conducted to explore the reaction mechanism and reveal that the byproduct formed in situ is the catalyst for this reaction and a tether derived from trifluoropyruvate is a key intermediate for this reaction.

Reductant-Free Aerobic Hydroxylation of Isoquinoline-1,3(2 H,4 H)-dione Derivatives.

Base-catalyzed efficient hydroxylation of isoquinoline-1,3(2 H,4 H)-diones with air under transition-metal-free and reductant-free conditions was established. This methodology is essentially mild and compatible with a broad range of substrates, including aryl, heteroaryl, and alkyl groups. Also, the product could be simply transformed into a hydroxylated tetrahydroisoquinoline core structure through a reductive process.

Palladium-catalyzed direct C(sp)-H arylation of indole-3-ones with aryl halides: a novel and efficient method for the synthesis of nucleophilic 2-monoarylated indole-3-ones.

A novel and efficient method for the synthesis of nucleophilic 2-monoarylated indole-3-ones palladium-catalyzed direct C(sp)-H arylation of indole-3-ones with aryl halides has been developed. Various 2-monoarylated indole-3-ones were readily obtained with yields up to 95%. As a class of important nucleophilic intermediates, 2-monoarylated indole-3-ones can be used for the construction of C2-quaternary indolin-3-one skeletons.

Synthesis of 4-Aryl Isoquinolinedione Derivatives by a Palladium-Catalyzed Coupling Reaction of Aryl Halides with Isoquinoline-1,3(2 H,4 H)-diones.

The palladium-catalyzed cross-coupling reaction of aryl halides with isoquinoline-1,3(2 H,4 H)-diones for the synthesis of 4-aryl isoquinoline-1,3(2 H,4 H)-diones was developed. The reaction conditions exhibit remarkable compatibility with various aryl halides and isoquinoline-1,3(2 H,4 H)-diones, and the product could be conveniently transformed to 4-aryl tetrahydroisoquinolines. (±) Dichlorofensine was synthesized using this protocol in two steps with an overall yield of 71%.

Disruption of biofilm formation by the human pathogen Acinetobacter baumannii using engineered quorum-quenching lactonases.

Acinetobacter baumannii is a major human pathogen associated with multidrug-resistant nosocomial infections; its virulence is attributed to quorum-sensing-mediated biofilm formation, and disruption of biofilm formation is an attractive antivirulence strategy. Here, we report the first successful demonstration of biofilm disruption in a clinical isolate of A. baumannii S1, using a quorum-quenching lactonase obtained by directed evolution; this engineered lactonase significantly reduced the biomass of A.

Pentanidium-catalyzed enantioselective α-hydroxylation of oxindoles using molecular oxygen.

Pentanidium-catalyzed α-hydroxylation of 3-substituted-2-oxindoles using molecular oxygen has been developed with good yields and enantioselectivities. This reaction does not require an additional reductant such as triethyl phosphite, which was typically added to reduce the peroxide intermediate. The reaction was demonstrated to consist of two-steps: an enantioselective formation of hydroperoxide oxindole and a kinetic resolution of the hydroperoxide oxindole via reduction with enolates generated from the oxindoles.

Expanding the utility of Brønsted base catalysis: biomimetic enantioselective decarboxylative reactions.

As a result of the low reactivity of simple esters, the use of them as nucleophiles in direct asymmetric transformations is a long-standing challenge in synthetic organic chemistry. Nature approaches this difficulty through a decarboxylative mechanism, which is used for polyketide synthesis. Inspired by nature, we report guanidine-catalyzed biomimetic decarboxylative C-C and C-N bond-formation reactions.