A Highly Efficient Gold-Catalyzed Oxidative C[BOND]C Coupling from C[BOND]H Bonds Using Air as Oxidant

A breath of fresh air: The title reaction has been developed for the coupling of amines with nitroalkanes and different unmodified ketones using air as the sole oxidant under mild reaction conditions. The safe, convenient, and environmentally benign process, as well as the low catalyst loading, short reaction time, and good yields make this protocol very practical (see scheme).

Highly Regioselective Copper-Catalyzed Benzylic C[BOND]H Amination by N-Fluorobenzenesulfonimide

Primary target: A practical and effective copper-catalyzed amination strategy for synthesizing various benzylic amines from benzylic hydrocarbons is described (see scheme; DCE=1,2-dichloroethane). Xylene substrates can undergo diamination reactions using this method. The remarkable preference for primary over secondary benzylic CH bonds has been observed for the first time.

Non-lattice surface oxygen species implicated in the catalytic partial oxidation of decane to oxygenated aromatics

DNA nanotechnology: The world's smallest assembly line

Palladium-Catalyzed Intermolecular Coupling of 2-Silylaryl Bromides with Alkynes: Synthesis of Benzosiloles and Heteroarene-Fused Siloles by Catalytic Cleavage of the C(sp3)[BOND]Si Bond

Intramolecular Redox-Triggered C[BOND]H Functionalization

Palladium-Catalyzed Carbonylative Dimerization of Styrenes to 1,5-Diarylpent-1-en-3-ones

Palladium-Catalyzed Carbonylation of Amines: Switchable Approaches to Carbamates and N,N′-Disubstituted Ureas

A Novel Sodium Nitrite-Catalyzed Oxidative Coupling for Constructing Polymethoxyphenanthrene Rings

Palladium-Catalyzed Direct and Site-Selective Desulfitative Arylation of Indoles with Sodium Sulfinates

Palladium-Catalyzed Oxidative C[BOND]C Bond Cleavage Cyclization of Biaryl-2-amines with Alkenes Involving C[BOND]H Olefination and Carboamination

A new indole incorporated chemosensor exhibiting selective colorimetric and fluorescence ratiometric signaling of fluoride

A method for the synthesis of 2-aminobenzoxazoles

Abstract

A synthesis of 2-aminobenzoxazoles from the parent C–H compound is described. The procedure involves deprotonation at the 2-position of the benzoxazole and quenching the intermediate organolithium species with a halogen electrophile. The 2-halobenzoxazole is then treated in the same pot with an amine nucleophile to afford the desired product. The substrate scope and selectivity of the reaction are presented. The method is operationally simple and provides access to a variety of amine products bearing additional nucleophilic heteroatoms.

A Unique Class of Near-Infrared Functional Fluorescent Dyes with Carboxylic-Acid-Modulated Fluorescence ON/OFF Switching: Rational Design, Synthesis, Optical Properties, Theoretical Calculations, and Applications for Fluorescence Imaging in Living Animals

Fluorescence imaging is one of the most powerful techniques for monitoring biomolecules in living systems. Fluorescent sensors with absorption and emission in the near-infrared (NIR) region are favorable for biological imaging applications in living animals, as NIR light leads to minimum photodamage, deep tissue penetration, and minimum background autofluorescence interference. Herein, we have introduced a new strategy to design NIR functional dyes with the carboxylic-acid-controlled fluorescence on–off switching mechanism by the spirocyclization. Based on the design strategy, we have developed a series of Changsha (CS1–6) NIR fluorophores, a unique new class of NIR functional fluorescent dyes, bearing excellent photophysical properties including large absorption extinction coefficients, high fluorescence quantum yields, high brightness, good photostability, and sufficient chemical stability. Significantly, the new CS1–6 NIR dyes are superior to the traditional rhodamine dyes with both absorption and emission in the NIR region while retaining the rhodamine-like fluorescence ON-OFF switching mechanism. In addition, we have performed quantum chemical calculations with the B3LYP exchange functional employing 6-31G* basis sets to shed light on the structure-optical properties of the new CS1–6 NIR dyes. Furthermore, using CS2 as a platform, we further constructed the novel NIR fluorescent TURN-ON sensor 7, which is capable of imaging endogenously produced HClO in the living animals, demonstrating the value of our new CS NIR functional fluorescent dyes. We expect that the design strategy may be extended for development of a wide variety of NIR functional dyes with a suitable fluorescence-controlled mechanism for many useful applications in biological studies.

Synthesis of a [2.2]paracyclophane based planar chiral palladacycle by a highly selective kinetic resolution/C–H activation reaction