Palladium-Catalyzed Synthesis of Six-Membered Benzofuzed Phosphacycles via Carbon–Phosphorus Bond Cleavage

The palladium-catalyzed synthesis of dibenzofused six-membered phosphacycles via carbon–phosphorus bond cleavage is developed. This method is compatible with a range of functional groups, such as esters, amides, and carbamates, which is in sharp contrast to the limitations of the classical method using organolithium reagents

Nickel-Catalyzed Cross-Coupling of Anisoles with Alkyl Grignard Reagents via C–O Bond Cleavage

Nickel-catalyzed cross-coupling of methoxyarenes with alkyl Grignard reagents, which involves the cleavage of the C­(aryl)–OMe bond, has been developed. The use of 1,3-dicyclohexylimidazol-2-ylidene as a ligand allows the introduction of a variety of alkyl groups, including Me, Me₃SiCH₂, ArCH₂, adamantyl, and cyclopropyl. The method can also be used for the alkylative elaboration of complex molecules bearing a C­(aryl)–OMe bond

C–H Functionalization at Sterically Congested Positions by the Platinum-Catalyzed Borylation of Arenes

Despite significant progress in the area of C–H bond functionalization of arenes, no general method has been reported for the functionalization of C–H bonds at the sterically encumbered positions of simple arenes, such as mesitylene. Herein, we report the development of the first platinum-based catalyst for C–H borylation of arenes and heteroarenes. Notably, this method exhibited high tolerance toward steric hindrance and provided rapid access to a series of 2,6-disubstituted phenylboronic esters, valuable building blocks for further elaborations

Nickel-Catalyzed Reductive and Borylative Cleavage of Aromatic Carbon–Nitrogen Bonds in N‑Aryl Amides and Carbamates

The nickel-catalyzed reaction of N-aryl amides with hydroborane or diboron reagents resulted in the formation of the corresponding reduction or borylation products, respectively. Mechanistic studies revealed that these reactions proceeded via the activation of the C­(aryl)–N bonds of simple, electronically neutral substrates and did not require the presence of an ortho directing group

Nickel-Catalyzed Formal Homocoupling of Methoxyarenes for the Synthesis of Symmetrical Biaryls via C–O Bond Cleavage

A new method has been developed for the nickel-catalyzed homocoupling of methoxyarenes via C–O bond cleavage using a diboron reagent. The use of 1,3-dicyclohexylimidazol-2-ylidene as a ligand was found to be critical to the success of the reaction. This new method allows the synthesis of a wide range of biaryl compounds

Palladium-Catalyzed Addition of Trifluoroacetylsilanes to Alkenes and Allenes via the Cleavage of C–Si Bonds

The palladium-catalyzed addition of trifluoroacetylsilanes to alkenes and allenes via the cleavage of the C–Si bonds is reported. When alkenes are used, cyclopropanation occurs to afford cyclopropane derivatives bearing CF3 and siloxy groups with a high degree of stereoselectivity. When allenes are used, silylacylation occurs to form alkenylsilane derivatives bearing a trifluoroacetyl group at the allylic position with complete regioselectivity. Both reactions allow for highly atom-economical access to densely functionalized fluorinated organosilane derivatives using simple building blocks

Rhodium-Catalyzed C–O Bond Alkynylation of Aryl Carbamates with Propargyl Alcohols

The rhodium-catalyzed alkynylation of aryl carbamates with propargyl alcohols is described. This methodology can provide aryl acetylenes from aryl carbamates via C–O bond activation. The use of propargyl alcohols as alkynylating agents allows the use of a variety of functional groups that are incompatible with organometallic nucleophiles. This reaction also serves to broaden the utility of a carbamate moiety as a convertible <i>ortho</i> directing group

Palladium-Catalyzed Direct <i>ortho</i>-Alkynylation of Aromatic Carboxylic Acid Derivatives

The palladium-catalyzed direct alkynylation of C–H bonds in aromatic carboxylic acid derivatives is described. The use of 8-aminoquinoline as a directing group facilitates the alkynylation of an electronically diverse range of C(sp²)–H bonds

Palladium-Catalyzed Synthesis of 2,3-Disubstituted Benzothiophenes via the Annulation of Aryl Sulfides with Alkynes

A new method has been developed for the synthesis of 2,3-disubstituted benzothiophenes involving the palladium-catalyzed annulation of aryl sulfides with alkynes. This convergent approach exhibited good functional group tolerance, providing rapid access to a diverse array of derivatives from simple, readily available starting materials. This protocol can also be used to synthesize 2-silyl-substituted benzothiophenes, which can be used as versatile platforms for the synthesis of 2,3-unsymmetrically substituted benzothiophenes

Nickel/Photoredox Dual-Catalyzed Conversion of Allyl Esters to Ketones via the Formal Deletion of Oxygen

We report herein the catalytic conversion of allylic esters into the corresponding ketones by the formal deletion of an oxygen atom. The key to the success of the reaction is the dual use of nickel and photoredox catalysts; the former mediates C–O bond activation and C–C bond formation, while the latter is responsible for deoxygenation of the acyloxy group using PPh3 as a stoichiometric reductant. Catalytic replacement of an oxygen atom of an allyl ester with a tethered alkene is also accomplished