Search

Cobalt(III) and rhodium(III)-catalyzed regio- and chemoselective amidation of benzocyclobutenols has been realized using dioxazolone as the amidating reagent to afford three classes of C-N-coupled products via β-carbon elimination of the benzocyclobutenol. The Co(III)-catalyzed coupling initially afforded an isolable o -( N -acylamino)arylmethyl ketone, which could further cyclize to the corresponding indole derivatives under condition control. In contrast, efficient stepwise diamidation has been achieved under Rh(III) catalyst control. The chemoselectivities are jointly controlled by the catalyst and reactions conditions.

Rhodium-catalyzed regio- and stereoselective three-component carboamidation of 1,3-enynes has been realized using indoles and dioxazolones as the functionalizing reagents. A wide range of multi-substituted skipped 1,4-dienes have been constructed in good yields and excellent stereoselectivity. The stereoselectivity is under substrate control. 1,3-Enynes bearing a relatively bulky alkyne terminus reacted with Z-selectivity. In contrast, a sterically less hindered alkyne terminus tends to predominantly give the E-configured skipped diene. [ABSTRACT FROM AUTHOR]

C−H bond activation has been established as an attractive strategy to access axially chiral biaryls, and the most straightforward method is direct C−H arylation of arenes. However, the arylating source has been limited to several classes of reactive and bulky reagents. Reported herein is rhodium‐catalyzed 1:2 coupling of diarylphosphinic amides and diarylacetylenes for enantio‐ and diastereoselective construction of biaryls with both central and axial chirality. This twofold C−H activation reaction stays contrast to the previously explored Miura–Satoh type 1:2 coupling of arenes and alkynes in terms of chemoselectivity and proceeded under mild conditions with the alkyne acting as a rare arylating reagent. Both C−H activation events are stereo‐determining and are under catalyst control, with the 2nd C−H activation being diastereo‐determining in a remote fashion. Analysis of the stereochemistry of the major and side products suggests moderate enantioselectivity of the initial C−H activation–desymmetrization process. However, the minor (R) rhodium vinyl intermediate is consumed more readily in undesired protonolysis, eventually resulting in high enantio‐ and diastereoselectivity of the major product. [ABSTRACT FROM AUTHOR]

Chiral RhIII catalysts can catalyze the asymmetric [4+1] spiroannulation of O-pivaloyl oximes with α-diazo homophthalimides under redox-neutral and acid/base-neutral conditions, leading to formation of chiral spirocyclic imines as a result of C–H activation and N–O cleavage. The reaction proceeded with high efficiency and features broad substrate scope, mild reaction conditions, and high to excellent enantioselectivities. [ABSTRACT FROM AUTHOR]

Reported herein is the rhodium(III)‐catalyzed C−H activation of anilines bearing an N‐isoquinolyl directing group for oxidative [3+2] annulation with four classes of internal alkynes, leading to atroposelective indole synthesis via dynamic kinetic annulation with C‐N reductive elimination constituting the stereo‐determining step. This reaction proceeds under mild conditions with high regio‐ and enantioselectivity and functional group compatibility. [ABSTRACT FROM AUTHOR]

Rhodium(III)-catalyzed C–C coupling of heteroarenes and fluorinated α-diazo diketones has been realized for the facile synthesis of 3-arylchromones. The reaction proceeds via chelation-assisted C–H activation, carbene insertion, and uncatalyzed intramolecular nucleophilic aromatic substitution, with C–F cleavage being accommodated in the nucleophilic aromatic substitution step. Three classes of heteroarenes have been defined with decent functional group tolerance. [ABSTRACT FROM AUTHOR]

Rhodium(III)-catalyzed mild and oxidative [4+1] spiroannulation has been realized via C–H activation of oximes and benzoic acids with 1-diazonaphthelen-2(1H)-ones as coupling reagents. This transformation integrates C–H activation and dearomatization and provides a direct approach to spirocyclic isoindole N-oxides and isobenzofuranones with functional group tolerance. [ABSTRACT FROM AUTHOR]

Axial‐to‐central chirality transfer is an important strategy to construct chiral centers, where the axially chiral reagents are mostly limited to atropomerically stable ones. Reported herein is a RhIII‐catalyzed enantioselective spiroannulative synthesis of nitrones. The coupling proceeds via C−H arylation to give an atropomerically metastable biaryl, followed by intramolecular dearomative trapping under oxidative conditions with high degree of chirality transfer. [ABSTRACT FROM AUTHOR]

Regio‐ and stereoselective benzylic allylation of 8‐methylquinolines with (per)fluoroalkyl olefins has been realized via benzylic C−H activation and subsequent C−F cleavage. Both cobalt(III) and rhodium(III) catalysts can effect this transformation in good to high efficiency. The Rh(III)‐catalyzed system proceeded under moderate conditions with decent substrates scope, providing (Z)‐alkenyl fluorides with good to excellent regio‐ and stereoselectivity. [ABSTRACT FROM AUTHOR]