RESUMEN
An iridium-catalyzed remote site-switchable hydroarylation of alkenes was reported, delivering the products functionalized at the subterminal methylene and terminal methyl positions on an alkyl chain controlled by two different ligands, respectively, in good yields and with good to excellent site-selectivities. The catalytic system showed good functional group tolerance and a broad substrate scope, including unactivated and activated alkenes. More importantly, the regioconvergent transformations of mixtures of isomeric alkenes were also successfully realized. The results of the mechanistic studies demonstrate that the reaction undergoes a chain-walking process to give an [Ar-Ir-H] complex of terminal alkene. The subsequent processes proceed through the modified Chalk-Harrod-type mechanism via the migratory insertion of terminal alkene into the Ir-C bond followed by C-H reductive elimination to afford the hydrofunctionalization products site-selectively.
RESUMEN
Chiral tertiary alcohols are an important structural motif, however, the general and efficient methodologies for their synthesis are less reported. Herein, we report a Ni(ÐÐ)-catalyzed asymmetric alkenylation and arylation of aryl ketones with organoborons under air via a 1,5-metalate shift strategy to obtain chiral tertiary allylic alcohols and diaryl alcohols. The reaction demonstrates good functional group tolerance and delivers chiral tertiary alcohols with good to excellent results. Furthermore, this method can be applied to the late-stage modification of drugs and the efficient synthesis of natural products. Notably, the reaction proceeds through an outer-sphere mechanism. The Ni(II) complex functions both as a Lewis acid to activate the ketone and create a chiral environment, and as coordination bridge linking the ketone and the organoboron-derived "ate" complex, facilitating the 1,5-metalate shift without forming a C-Ni bond. This approach contrasts with traditional transition metal-catalyzed nucleophilic addition reactions that involve carbon-metal bond formation.
RESUMEN
There are only a few examples being reported for the simultaneous control of central chirality and axial chirality because it is more challenging. Herein, we report an iridium-catalyzed asymmetric hydroarylation of unactivated alkenes with heterobiaryls to simultaneously construct axial and central chirality. The reaction showed a broad substrate scope and delivered the products with satisfactory results. The results of the control experiments demonstrated that the FerroLANE ligand promotes the reaction to proceed along a specific modified Chalk-Harrod mechanism.
RESUMEN
The 1,3-rearrangement of allylic derivatives has rarely been reported, except for allylic alcohols. Herein, we describe an iridium-catalyzed 1,3-rearrangement of readily available allylic ethers to access the difficultly prepared allylic ethers with a large steric hindrance. The developed method shows a broad substrate scope and could be used in the late-stage modification of several natural products. In addition, a possible reaction pathway is also provided on the basis of the control experiments.