The transition-metal-catalyzed α-arylation of carbonyl compounds is a widely practiced method for C-C bond formation. Several enantioselective versions of this process have been reported, but intermolecular, enantioselective coupling reactions of aryl electrophiles with α-fluoro carbonyl compounds have yet to be disclosed. We report enantioselective coupling of aryl and heteroaryl bromides and triflates with α-fluoroindanones catalyzed by palladium complexes of a BINOL-derived monophosphine and Segphos, respectively. The enolates were generated directly from α-fluoroindanones in the presence of potassium phosphate base during the reactions. We also report that reactions of α-fluorotetralones occur in high yields and enantioselectivities when conducted with enolates generated by elimination of trifluoroacetate from trifluoromethyl β-diketone hydrates. These reactions were catalyzed by palladium complexes of the commercially available bisphosphine Difluorphos. Thus, the formation of enantioenriched α-aryl-α-fluoroketones can be readily achieved by C-C bond formation when the appropriate palladium catalyst and α-fluoro enolate precursor were used.

Regioselective functionalization of arenes remains a challenging problem in organic synthesis. Steric interactions are often used to block sites adjacent to a given substituent, but they do not distinguish the remaining remote sites. We report a strategy based on remote steric control, whereby a roof-like ligand protects the distant para site in addition to the ortho sites, and thereby enables selective activation of meta carbon-hydrogen (C–H) bonds in the absence of ortho or para substituents. We demonstrate this concept for iridium-catalyzed meta -selective borylation of various monosubstituted arenes, including complex drug molecules. This strategy has the potential to expand the toolbox of C–H bond functionalization to previously nondifferentiable reaction sites.

Transition-metal-catalyzed asymmetric α-arylation of carbonyl compounds is a widely studied method for C-C bond formation. Recently, the α-arylation of α-fluoro ketones has been reported, including enantioselective α-arylation of α-fluoro ketones. However, the asymmetric α-arylation of α-fluoro carbonyl compounds in the carboxylic acid oxidation state has not been reported. We report the enantioselective α-arylation of α-fluorooxindoles with aryl triflates. The reaction occurs in high yield and with high enantioselectivity when catalyzed by a Pd-Segphos complex. This general class of product serves as an enantioenriched, nonenolizable version of α-aryl oxindoles.

A chemoselective hydrogenation of isoquinoline carbocycles was achieved by using the catalyst prepared from Ru(methallyl)(cod) and trans-chelate chiral ligand PhTRAP. The unique chemoselectivity achieved in this hydrogenation could be ascribed to the trans-chelation of the chiral ligand. The procedure for preparing the catalyst strongly affects the reproducibility of the carbocycle hydrogenation. Various 5-, 6-, 7-, and 8-substituted isoquinolines were selectively hydrogenated at their carbocycles to afford 5,6,7,8-tetrahydroisoquinolines as major products in high yields with moderate or good enantioselectivities. Some mechanistic studies suggested that the stereogenic center was created during the initial addition of H to the aromatic ring in the hydrogenation of 5-substituted isoquinolines. In other words, the stereochemical control was accompanied by the dearomatization.

Invited for this month′s cover is the group of Nobuharu Iwasawa at Tokyo Institute of Technology. The image shows a switchable site‐selective carboxylation between benzylic C−O and aryl C−Cl moieties enabled by a palladium/iridium dual catalyst under visible light irradiation. The Communication itself is available at 10.1002/cssc.202102095.