Xin Mu

Palladium-Catalyzed Oxidative Aryltrifluoromethylation of Activated Alkenes at Room Temperature

A palladium-catalyzed intramolecular oxidative aryltrifluoromethylation reaction of activated alkenes has been explored. The reaction allows for an efficient synthesis of a variety of CF(3)-containing oxindoles. Preliminary mechanistic study indicated that the reaction involves a C(sp(3))-Pd(IV)(CF(3)) intermediate, which undergoes reductive elimination to afford a C(sp(3))-CF(3) bond.

Palladium‐Catalyzed Oxidative Arylalkylation of Activated Alkenes: Dual CH Bond Cleavage of an Arene and Acetonitrile

Not one but two: The title reaction proceeds through the dual C-H bond cleavage of both aniline and acetonitrile. The reaction affords a variety of cyano-bearing indolinones in excellent yield. Mechanistic studies demonstrate that this reaction involves a fast arylation of the olefin and a rate-determining C-H activation of the acetonitrile.

Palladium‐Catalyzed Oxidative Trifluoromethylation of Indoles at Room Temperature

Incorporation of fluorine atoms into organic molecules significantly enhances many of their properties, such as solubility, metabolic stability, and bioavailability. Among organofluorine molecules, trifluoroACHTUNGTRENNUNGmethylated compounds play a unique and important role in agricultural and medicinal chemistry. As a consequence, the exploitation of efficient methods to construct C CF3 bond has received much attention. The introduction of a CF3 moiety onto aromatic compounds is generally achieved by using the Swarts reaction or the cross-couplings of aromatic halides with a stoichiometric amount of CuCF3 reagents generated in situ. Recent studies demonstrated that the formation of Aryl C CF3 bonds could be achieved through a reductive elimination of palladium complexes (Ar)Pd CF3 in different reaction conditions. Several major progresses on this challenging transformation have been made by using a catalytic amount of palladium catalysts.

Copper-Catalyzed Intermolecular Trifluoromethylarylation of Alkenes: Mutual Activation of Arylboronic Acid and CF3+ Reagent

A novel copper-catalyzed intermolecular trifluoromethylarylation of alkenes is developed using less active ether-type Tognis reagent under mild reaction conditions. Various alkenes and diverse arylboronic acids are compatible with these conditions. Preliminary mechanistic studies reveal that a mutual activation process between arylboronic acid and CF3(+) reagent is essential. In addition, the reaction might involve a rate-determining transmetalation, and the final aryl C-C bond is derived from reductive elimination of the aryl(alkyl)Cu(III) intermediate.

Silver-Catalyzed Intramolecular Aminofluorination of Activated Allenes†

A nice combination: the intramolecular oxidative aminofluorination of allenes using silver catalysis and FN(SO(2)Ph)(2) as the fluorinating reagent has been developed. This reaction represents an efficient method for the synthesis of various 4-fluoro-2,5-dihydropyrrole compounds. Further transformation provided the corresponding fluorinated pyrrole derivatives in good yields.

Highly Selective Pd-Catalyzed Intermolecular Fluorosulfonylation of Styrenes

A novel Pd-catalyzed intermolecular regio- and diastereoselective fluorosulfonylation of styrenes has been developed under mild conditions. This reaction exhibits a wide range of functional-group tolerance in styrenes and arylsulfinic acids to afford various β-fluoro sulfones. Preliminary mechanistic study reveals an unusual mechanism, in which a high-valent L2Pd(III)F species side-selectively reacts with a benzylic carbon radical to deliver a C-F bond. This pathway is distinct from a previously reported radical fluorination reaction.

Copper-Catalyzed Trifluoromethylthiolation of Aryl Halides with Diverse Directing Groups

The expansion of cross-coupling components in Cu-catalyzed C-X bond forming reactions have received much attention recently. A novel Cu-catalyzed trifluoromethylthiolation of aryl bromides and iodides with the assistance of versatile directing groups such as pyridyl, methyl ester, amide, imine and oxime was reported. CuBr was used as the catalyst, and 1,10-phenanthroline as the ligand. By changing the solvent from acetonitrile to DMF, the coupling process could even take place at room temperature.

Copper‐Catalyzed Regioselective Fluorination of Allylic Halides

Group activity: A novel copper-catalyzed fluorination of internal allylic bromides and chlorides has been developed by using Et3N⋅3 HF as the fluorine source. A functional group (FG) within the substrate is required to achieve the allylic fluorination, and a variety of secondary allylic fluoride compounds can be accessed in good yield with excellent regioselectivity.

Copper-catalyzed fluorination of 2-pyridyl aryl bromides

Copper(I)-catalyzed cross-coupling of aryl halides is the subject of extensive interest in synthetic chemistry, but the related catalytic fluorination is unsuccessful. Herein, we have developed a novel copper-catalyzed fluorination of aryl bromides using AgF as the fluorine source. In this transformation a pyridyl directing group is essential for successful catalytic fluorination. A XANES/EXAFS study indicated that the presence of the pyridyl group is essential to stabilize the Cu(I) species and accelerate oxidative addition of the aryl bromide. Further mechanistic studies implicated a Cu(I/III) catalytic cycle in this Cu(I)-catalyzed fluorination, and final aryl C–F bond formation possibly proceeds through an irreversible reductive elimination of the ArCu(III)–F species. This rare report of catalytic fluorination by a copper catalyst provides a valuable foundation for further development of Cu(I)-catalyzed fluorination of aryl halides.

Copper-mediated/-catalyzed fluorination reactions: new routes to aryl fluorides

Recently, a series of transition metals have been extensively explored for the construction of aryl C–F bonds. The introduction of inexpensive copper reagents instead of Pd and Ag complexes would be promising methods for scalable production of aryl fluorides without concomitant hazardous wastes. This highlight mainly focused on recent advances in copper-mediated/-catalyzed fluorination reactions to construct aryl fluorides.