Mechanistic Switch via Subtle Ligand Modulation: Palladium-Catalyzed Synthesis of α,β-Substituted Styrenes via CH Bond Functionalization

Palladium-Catalyzed Access to Benzocyclobutenone-Derived Ketonitrones via C(sp2)-H Functionalization

The palladium-catalyzed C(sp2)-H functionalization of bromoaryl aldonitrones leading to benzocyclobutenone-derived ketonitrones is described. This method allows for the preparation of a wide range of strained, four-membered ketonitrones with broad functional group tolerance. Downstream transformations of the formed products were readily demonstrated, illustrating the synthetic utility of the obtained benzocyclobutenone-derived nitrones for the construction of polycyclic nitrogen-containing scaffolds.

Palladium-Catalyzed Cross-Coupling of gem-Bis(boronates) with Aryl Halides: An Alternative To Access Quaternary α-Aryl Aldehydes

The compounds with a quaternary α-aryl aldehyde skeleton are important units in organic chemistry. Previously, the aryl group and carbonyl group are introduced in a stepwise manner. Herein, a novel route is developed to construct the quaternary α-aryl aldehydes with gem-bis(boronates) as precursors, in which the two groups are installed simultaneously. The gem-bis(boronates) are readily available from ketones; as a result, this methodology provides a more general strategy to produce the quaternary α-aryl aldehydes with broad scopes and synthetic convenience.

Selective Formation of Internal Olefinic Trimer of α-Methylstyrenes with HI Gas and Ketones

Reaction of α-methylstyrene in the presence of HI gas and methyl p-tolyl ketone selectively resulted in an internal olefinic trimer. We revealed that the ketones with the stabilization of the protonated state were efficient to give the corresponding trimers, whereas the other ketones gave the usual indane compound. From the investigation for the mechanistic path, we found that the trimer is a kinetic product and that indane is a thermodynamic product.

Cu-catalyzed mild C(sp2)-H functionalization assisted by carboxylic acids en route to hydroxylated arenes

A formal Cu-catalyzed C(sp(2))-H hydroxylation assisted by benzoic acids is described. The procedure is characterized by its mild reaction conditions and wide substrate scope utilizing simple and cheap Cu catalysts, thus becoming a user-friendly and operationally simple protocol for C(sp(2))-H hydroxylation.

Pd-catalyzed tandem cyclization of ethyl glyoxalate and amines: rapid assembly of highly substituted cyclic dehydro-α-amino acid derivatives

A novel cascade cyclization of ethyl glyoxalate and amines proceeds in the presence of Pd(TFA)(2) (5 mol %) to give the cyclic dehydro-α-amino acid derivatives. This method provides a fast and simple access to highly substituted dihydro-pyrrol-2-ones in good yields.

Rhodium-catalyzed oxidative C2-acylation of indoles with aryl and alkyl aldehydes

A rhodium-catalyzed oxidative C2-acylation of indoles with aryl and alkyl aldehydes via C-H bond activation is described. The reaction is highly atom-economic and provides easy access to a wide variety of 2-aroylindoles.