Palladium-catalyzed organometallic transformations of free amines are often unsuccessful due to side reactions, such as oxidation, that can occur. However, the ability to furnish the free amine products from these reactions is important for improving the utility and sustainability of these processes, especially for accessing their potential as medicinal and agrochemical agents. Notably, the 3,3-diarylallylamine motif is prevalent in a variety of biologically relevant structures, yet there are few catalytic approaches to their synthesis, and none involving the free amine. Herein, we describe a simple protocol for the arylation of cinnamylamines and the diarylation of terminal allylamines to generate a diverse group of 3,3-diarylallylamine products using a Pd II precatalyst. Key features of the method are the ability to access relatively mild conditions that facilitate a broad substrate scope as well as direct diarylation of terminal allylamine substrates. In addition, several complex and therapeutically relevant molecules are included to demonstrate the utility of the transformation.

Herein is presented a general strategy to perform reactions under mild to moderate CO2 pressures with dry ice. This technique obviates the need for specialized equipment to achieve modest pressures, and can even be used to achieve higher pressures in more specialized equipment and sturdier reaction vessels. At the end of the reaction, the vials can be easily depressurized by opening at room temperature. In the present example CO2 serves as both a putative directing group as well as a way to passivate amine substrates, thereby preventing oxidation during the organometallic reaction. In addition to being easily added, the directing group is also removed under vacuum, obviating the need for extensive purification to remove the directing group. This strategy allows the facile γ-C(sp)-H arylation of aliphatic amines and has the potential to be applied to a variety of other amine-based reactions.

Amines are an important class of compounds in organic chemistry and serve as an important motif in various industries, including pharmaceuticals, agrochemicals, and biotechnology. Several methods have been developed for the C–H functionalization of amines using various directing groups, but functionalization of free amines remains a challenge. Here, we discuss our recently developed carbon dioxide driven highly site-selective γ-arylation of alkyl- and benzylic amines via a palladium-catalyzed C–H bond-activation process. By using carbon dioxide as an inexpensive, sustainable, and transient directing group, a wide variety of amines were arylated at either γ-sp3 or sp2 carbon–hydrogen bonds with high selectivity based on substrate and conditions. This newly developed strategy provides straightforward access to important scaffolds in organic and medicinal chemistry without the need for any expensive directing groups.1 Introduction2 C(sp3)–H Arylation of Aliphatic Amines3 C(sp2)–H Arylation of Benzylamines4 Mechanistic Questions5 Future Outlook

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