Nickel(0)-Catalyzed Enantioselective [3+2] Annulation of Cyclopropenones and α,β-Unsaturated Ketones/Imines

Ni⁰-catalyzed chemo- and enantioselective [3+2] cycloaddition of cyclopropenones and α,β-unsaturated ketones/imines is described. This reaction integrates C−C bond cleavage of cyclopropenones and enantioselective functionalization by carbonyl/imine group, offering a mild approach to γ-alkenyl butenolides and lactams in excellent enantioselectivity (88–98 % ee) through intermolecular C−C activation.     

Enantioselective Cross‐Exchange between C−I and C−C σ Bonds

A palladium‐catalyzed enantioselective intramolecular σ‐bond cross‐exchange between C?I and C?C bonds is realized, providing chiral indanones bearing an alkyl iodide group and an all‐carbon quaternary stereocenter. Pd/TADDOL‐derived phosphoramidite is found to be an efficient catalytic system for both C?C bond cleavage and alkyl iodide reductive elimination. In addition to aryl iodides, aryl bromides can also be used for this transformation in the presence of KI. Density‐functional theory (DFT) calculation studies support the ring‐opening of cyclobutanones occuring through an oxidative addition/reductive elimination process involving Pd^IV species.     

Selective Arene Cleavage by Direct Insertion of Iridium into the Aromatic Ring

We report an unprecedented selective cleavage of aromatic C−C bonds through the insertion of well‐defined iridium complexes into the aromatic ring of simple alkylarenes. The insertion occurs at 50–100 °C without the activation of weaker C−H and C−C bonds and gives unique metallacycles in high yields. Key to the success of this approach is metal‐induced deformation of the arene ring, which creates temporary ring strain and promotes direct and selective insertion of the metal into the otherwise inert arene ring C−C bonds.     

Carbonylative C−C Bond Activation of Electron‐Poor Cyclopropanes: Rhodium‐Catalyzed (3+1+2) Cycloadditions of Cyclopropylamides

Rh‐catalyzed carbonylative C?C bond activation of cyclopropylamides generates configurationally stable rhodacyclopentanones that engage tethered alkenes in (3+1+2) cycloadditions. These studies provide the first examples of multicomponent cycloadditions that proceed through C?C bond activation of “simple” electron poor cyclopropanes.