Chiral Cp‐Rhodium(III)‐Catalyzed Asymmetric Hydroarylations of 1,1‐Disubstituted Alkenes

Abstract

Metal-catalyzed functionalizations at the ortho position of a directing group have become an efficient bond-forming strategy. A wide range of transformations that employ Cp*Rh(III) catalysts have been described, but despite their synthetic potential, enantioselective variants that use chiral versions of the Cp* ligand remain scarce (Cp*=pentamethyl cyclopentadienyl). Cyclopentadienyl compounds with an atropchiral biaryl backbone are shown to be suitable ligands for the efficient intramolecular enantioselective hydroarylation of aryl hydroxamates. Dihydrofurans that bear methyl-substituted quaternary stereocenters are thus obtained by CH functionalization under mild conditions.

Rh‐Catalyzed Synthesis of Oxygen‐Containing Heterocycles

“…More recently, Cramer and coworkers reported an asymmetric version of this chemistry to access functionalized chiral dihydrobenzofurans that possess a quaternary stereocenter using chiral rhodium catalyst (Scheme 6.13) [23]. They found that O-tethered substrate 54 was deuterated more quickly than metamethyl-substituted derivative 55.…”

Mild metal-catalyzed C–H activation: examples and concepts

“…Using another Cp derivative as a chiral ligand on Rh, high enantioselectivities were achieved at room temperature, demonstrating that the intramolecular alkene insertion is a more efficient process than the corresponding intermolecular variant. 137 Ma's group devised a transformation combining allene carborhodation and subsequent cyclization with a tethered olefin to prepare polycyclic products featuring eight-membered lactams. 138 …”

Chiral Carboxylic Acid Enabled Achiral Rhodium(III)‐Catalyzed Enantioselective C−H Functionalization

“…[4] Enantioselective C À Hf unctionalization has recently attracted much attention for the synthesis of complex molecules including chiral stereocenters. [5] In this context, the group of Cramer reported that Rh III [6] and Ir III[7] complexes bearing precisely designed chiral Cp x ligands enabled catalytic asymmetric CÀHf unctionalization reactions. [8] The groups of You [9] and Antonchick and Waldmann [10] also developed different types of chiral Cp x ligands.T hese designed Cp x ligands greatly facilitated the development of enantioselective CÀHf unctionalization reactions (Scheme 1a).…”