Ruthenium-Catalyzed ortho-C-H Hydroxyfluoroalkylation of Arenes with Fluorinated Alcohols.

A facile and mild Ru(II)-catalyzed ortho-C-H hydroxyfluoroalkylation of arenes with cheap and easily accessible fluorinated alcohols has been developed in the presence of 2,2,6,6-tetramethyl-1-piperidinyloxyl (TEMPO). The readily available fluorinated alcohols were used as hydroxyfluoroalkylation reagents to form various α-aryl-α-trifluoromethyl alcohols. The present work provides a new method for the introduction of hydroxyfluoroalkyl groups into arenes.

Metal-free alkylation of quinoxalinones with aryl alkyl ketones.

The first metal-free method for alkylation of quinoxalinones using cheap and stable aryl alkyl ketones as nucleophilic alkylation reagents is reported. This strategy greatly broadens the application channels of aryl alkyl ketones through carbon-carbon bond activation. In addition, the protocol has the advantages of simple operation, broad substrate scope, and good functional group tolerance.

Copper-promoted difunctionalization of unactivated alkenes with silanes.

An efficient copper-catalyzed cascade difunctionalization of N-allyl anilines toward the synthesis of silylated indolines using commercially available silanes has been reported. This strategy provides a new avenue for the synthesis of a diverse array of indolines in reasonable yields. Preliminary mechanistic investigations indicate that the reaction probably proceeds via a radical pathway with unactivated alkenes as radical acceptors and simple silanes as radical precursors. This protocol is distinguished by its atom economy, broad substrate scope and readily available starting materials.

[4 + 2] cycloaddition reactions of ß-naphtha-1-thioquinones generated from 2-naphthols and DAST.

An original and facile method for the generation of ß-naphtha-1-thioquinones using DAST and 2-naphthols has been developed. A series of dehydro-2-naphthol-1-sulphides or naphtha-oxathiane derivatives were synthesized by in situ Diels-Alder cycloaddition reactions of ß-naphtha-1-thioquinone with itself or various alkenes.

Visible-Light-Induced Direct Csp2-H Radical Trifluoroethylation of Coumarins with 1,1,1-Trifluoro-2-iodoethane (CF3CH2I).

Herein, we developed the first visible-light-induced direct Csp2-H radical 2,2,2-trifluoroethylation of coumarins with commercially available and cheap reagent CF3CH2I at room temperature. This transformation proceeded smoothly under mild conditions and showed excellent functional group compatibility. The synthetic value of the protocol was also demonstrated by the successful functionalization of several pharmaceuticals.

External oxidant-free alkylation of quinoline and pyridine derivatives.

A novel and efficient method for the generation of alkyl radicals and the alkylation of quinoline and pyridine derivatives under mild conditions has been developed. This strategy allows the direct alkylation of heteroaromatics in the absence of an external oxidant. A preliminary mechanistic study suggests that the present reaction probably proceeds via an intermolecular HAT process.

Palladium-Catalyzed Hiyama Cross-Couplings of Arylsilanes with 3-Iodoazetidine: Synthesis of 3-Arylazetidines.

The first palladium-catalyzed Hiyama cross-coupling reactions of arylsilanes with 3-iodoazetidine were described. The protocol provides a convenient access to a variety of useful 3-arylazetidines which are of great interest in pharmaceutical laboratories in moderate to good yields (30%-88%). In addition, this strategy has the advantage of easy operation and mild reaction conditions.

Transition-Metal-Free Oxidation of Benzylic C-H Bonds of Six-Membered N-Heteroaromatic Compounds.

A novel oxidation of benzylic C-H bonds for the synthesis of diverse six-membered N-heteroaromatic aldehydes and ketones has been developed. The obvious advantages of this approach are the simple operation, mild reaction conditions, and without use of toxic reagent and transition metal. The present method should provide a useful access for the synthesis and modification of N-heterocycles.

O-Difluorodeuteromethylation of phenols using difluorocarbene precursors and deuterium oxide.

The first O-difluorodeuteromethylation of phenols using commercial diethyl bromodifluoromethylphosphonate and deuterium oxide to prepare various difluorodeuteromethyl aryl ethers is reported. This facile method affords a convenient way to introduce OCF2D groups into organic molecules.

Palladium-Catalyzed Diastereoselective Synthesis of 3-Arylbutanoic Acid Derivatives.

The first palladium-catalyzed diastereoselective conjugate addition of arylboronic acids to chiral imides is reported. The catalytic system employing 4-tert-butyloxazolidin-2-one as the chiral auxiliary in a mixed solvent system of MeOH/H2O (1:3) under an air atmosphere provides the optically active 3-arylbutanoic acid derivatives in excellent yields with high diastereoselectivity.

CuI-Catalyzed Fluorodesulfurization for the Synthesis of Monofluoromethyl Aryl Ethers.

An efficient CuI-catalyzed fluorodesulfurization for the synthesis of monofluoromethyl aryl ethers using DAST at room temperature has been developed. This approach exhibits a good functional group tolerance, a broad substrate scope, and a high synthesis efficiency.

Regioselective Synthesis of N-Heteroaromatic Trifluoromethoxy Compounds by Direct O-CF3 Bond Formation.

The first one-step method for the synthesis of ortho-N-heteroaromatic trifluoromethoxy derivatives by site-specific O-CF3 bond formation using hydroxylated N-heterocycles and Togni's reagent is described. The approach enables the unprecedented syntheses of a wide range of six or five-membered N-heteroaromatic trifluoromethoxy compounds containing one or two heteroatoms from most commonly used hydroxylated N-heterocycles. Notable advantages of this method include its simplicity and mild conditions, avoidance of the need for metals or toxic reagents, and compatibility with a variety of functional groups. Furthermore, this method is especially suitable for the larger scale application.

An unprecedented Pd-catalyzed decarboxylative coupling reaction of aromatic carboxylic acids in aqueous medium under air: synthesis of 3-aryl-imidazo[1,2-a]pyridines from aryl chlorides.

An efficient and practical protocol for palladium-catalyzed decarboxylative arylation of imidazo[1,2-a]pyridine-3-carboxylic acids with aryl chlorides has been developed. Note that the reaction could proceed smoothly without an additive in aqueous medium under an ambient atmosphere, and the addition of H2O could effectively promote the decarboxylative arylation. Particularly noteworthy is that these results represent the first examples of Pd-catalyzed decarboxylative coupling reactions of (hetero) aromatic carboxylic acids in aqueous medium under air, and the first successful examples of the synthesis of 3-aryl-imidazo[1,2-a]pyridines using cheap, diverse aryl chlorides and heteroaryl chlorides as the starting materials.

Synthesis of 3,3-disubstituted oxindoles by visible-light-mediated radical reactions of aryl diazonium salts with N-arylacrylamides.

A mild and efficient visible-light-mediated diarylation of N-arylacrylamides with aryl diazonium salts under mild conditions has been developed. This method provides convenient access to a variety of useful 3,3-disubstituted oxindoles by constructing two C-C bonds in one step.

Copper-assisted trifluoromethylthiolation/radical cascade cyclization of alkynes to construct SCF3-containing dioxodibenzothiazepines.

A mild and efficient Cu-assisted trifluoromethylthiolation/radical cascade cyclization of alkynes with readily available and stable AgSCF3 as the trifluoromethylthiolating reagent has been disclosed. This transformation provides an opportunity to construct a series of potential medicinally valuable trifluoromethylthio-substituted dioxodibenzothiazepines with wide functional group compatibility. This protocol opens up a new avenue for the construction of useful trifluoromethylthiolated seven-membered N-heterocycles.

Visible-Light-Induced Radical Difluoromethylation/Cyclization of Unactivated Alkenes: Access to CF2H-Substituted Quinazolinones.

A mild and efficient visible-light-induced radical difluoromethylation/cyclization of unactivated alkenes toward the synthesis of substituted quinazolinones with easily accessible difluoromethyltriphenylphosphonium bromide has been developed. The transformation has the advantages of wide functional group compatibility, a broad substrate scope, and operational simplicity. The benign protocol offers a facile access to pharmaceutically valuable difluoromethylated polycyclic quinazolinones.

Light driven molecular lock comprises a Ru(bpy)2(hpip) complex and cucurbit[8]uril.

Here, complex 1 ([Ru(bpy)2(hpip)]2+-MV2+) and CB[8] can form a stable 1 : 1 inclusion complex in aqueous solution, resembling a U-shaped conformation. Upon light irradiation, two complex 1 were reversibly locked through the formation of a MV˙+ radical dimer that is stabilized in the cavity of CB[8] with Ru complexes as blockers, in which complex 1 was transformed from a U-shaped conformation to a interlocked complex. This study provided a feasible strategy for the fabrication of a photo-driven supramolecular machine resembling a "lock".

A new dinuclear ruthenium complex as an efficient water oxidation catalyst.

A dinuclear ruthenium complex, which acts as a molecular catalyst for water oxidation, has been synthesized and characterized. The electronic and electrochemical properties were studied by UV-vis spectroscopy and cyclic voltammetry. The oxidation potentials of the complex are significantly lowered by introducing a negatively charged carboxylate ligand, in comparison with those of the reported complexes that have neutral ligands. The catalytic activity of the complex toward water oxidation using Ce(NH(4))(2)(NO(3))(6) as a chemical oxidant was investigated by means of an oxygen electrode and mass spectrometry. The turnover number of this catalyst with Ce(IV) as the chemical oxidant was found to be ca. 1700. The mass spectroscopic analysis of the isotopomer distribution in oxygen evolved from (18)O-labeled water indicates that O atoms in the evolved oxygen originate from water.

Light driven formation of a supramolecular system with three CB[8]s locked between redox-active Ru(bpy)3 complexes.

Three CB[8]s have been reversibly locked between two Ru(bpy)(3)-viologen complexes by light driven electron transfer reactions.

Quinoline-based ratiometric fluorescent probe for detection of physiological pH changes in aqueous solution and living cells.

Herein, a novel quinoline-based fluorescent probe DQPH has been developed for ratiometric detection of subtle pH fluctuation in biosystem. Upon altering the pH from 4.50 to 9.00, the emission spectra exhibit a large hypsochromic shift (57 nm) and the ratio of fluorescence intensity (F531 nm/F588 nm) changes from 0.30 to 1.36 with an ideal pKa value of 7.18 and a linear pH variation range of 6.35-8.00. The ratiometric response is attributed to the protonation-activable resonance charge transfer (PARCT) process, which has been proved by 1H NMR and NOESY experiment. This probe displayed good solubility, low cytotoxicity, anti-interference capability and reversible pH sensing. Furthermore, DQPH was successfully applied for monitoring pH changes in living cells.