C-H Activation and Sequential Addition to Dienes and Imines: Synthesis of Amines with -Quaternary Centers and Mechanistic Studies on the Complex Interplay Between the Catalyst and Three Reactants.

A Rh(III)-catalyzed sequential C-H bond addition to dienes and in situ formed aldimines was developed, allowing for the preparation of otherwise challenging to access amines with quaternary centers at the -position. A broad range of dienes were effective inputs and installed a variety of aryl and alkyl substituents at the quaternary carbon site. Aryl and alkyl sulfonamide and carbamate nitrogen substituents were incorporated by using different formaldimine precursors.

Visible Light-Mediated, Highly Diastereoselective Epimerization of Lactams from the Most Accessible to the More Stable Stereoisomer.

Most known methods to access δ-lactams with stereogenic centers at the α- and β-positions are highly selective for the contra-thermodynamic diastereomer, typically hydrogenation of the corresponding pyridinones or quinolinones. We describe here the development of a photoredox-mediated hydrogen atom transfer (HAT) approach for the epimerization of δ-lactams to access the more stable diastereomers from the contra-thermodynamic isomers. The reaction displays broad functional group compatibility, including acid, ester, 1°, 2° and 3° amide, carbamate, and pyridyl groups, and was effective for a range of differently substituted monocyclic and bicyclic lactams.

C-H bond activation and sequential addition to two different coupling partners: a versatile approach to molecular complexity.

Sequential multicomponent C-H bond addition is a powerful approach for the rapid, modular generation of molecular complexity in a single reaction. In this approach, C-H bonds are typically added across π-bonds or π-bond isosteres, followed by subsequent coupling to another type of functionality, thereby forming two σ-bonds in a single reaction sequence. Many sequential C-H bond addition reactions have been developed to date, including additions across both conjugated and isolated π-systems followed by coupling with reactants such as carbonyl compounds, cyanating reagents, aminating reagents, halogenating reagents, oxygenating reagents, and alkylating reagents.

Three-Component 1,2-Carboamidation of Bridged Bicyclic Alkenes via Rh-Catalyzed Addition of C-H Bonds and Amidating Reagents.

A three-component method is described for the preparation of -1,2-disubstituted bridged bicyclic compounds. The reaction was demonstrated for readily available aromatic and heteroaromatic C-H bond substrates with tertiary and secondary amide, lactam, pyrazole, and triazole directing groups and a variety of bridged bicyclic alkenes, including norbornene, benzonorbornadiene, oxygen- and nitrogen-bridged analogs, and an unsaturated tropinone. A broad dioxazolone scope was also observed.