Oxygen‐Linked Cyclopentadienyl Rhodium(III) Complexes‐Catalyzed Asymmetric C−H Arylation of Benzo[h]quinolines with 1‐Diazonaphthoquinones

Abstract

Chiral cyclopentadienyl rhodium (CpRh) complexcatalyzeda symmetric CÀHf unctionalization reactions have witnessed as ignificant progress in organic synthesis.I ns harp contrast, the reported chiral Cp ligands are limited to C-linked Cp and are often synthetically challenging.T oa ddress these issues,w eh ave developed an ovel class of tunable chiral cyclopentadienyl ligands bearing oxygen linkers,w hich were efficient catalysts for CÀHa rylation of benzo[h]quinolines with 1-diazonaphthoquinones,a ffording axially chiral heterobiaryls in excellent yields and enantioselectivity (up to 99 % yield, 98.5:1.5 er). Mechanistic studies suggest that the reaction is likely to proceed by electrophilic C À Ha ctivation, and followed by coupling of the cyclometalated rhodium(III) complex with 1-diazonaphthoquinones.

Twofold C−H Activation‐Based Enantio‐ and Diastereoselective C−H Arylation Using Diarylacetylenes as Rare Arylating Reagents

“…transformation of arenes using heteroarenes as an arylating reagent. [12] Despite the progress,generation of axial chirality calls for employment of more readily available arylating reagents. Since 1-naphthyl groups represent at ypical bulky aryl ring, formation of 1-naphthyls offers ac onvenient approach to biaryl synthesis.I nt his context, Wang [13] reported in 2019 Satoh-Miura type [14] 1:2a nnulation between amides and alkynes for atroposelective synthesis of naphthalenes (Scheme 1a), where the alkyne contributes four carbon atoms to the naththalene ring (Type I coupling), and the axis preexists in the arene substrate,w hich amounts to dinamic kinetic transformation of the arene substrate.O nt he other hand, alternative role of alkynes may be invoked in ad ifferent chemoselectivity (Scheme 1b, Type II reaction) where the chiral axis is newly constructed.…”

Rhodium-Catalyzed Asymmetric C–H Functionalization Reactions

“…In 2021, You and co-workers realized asymmetric arylation of benzo[h]quinolines 345 with diazonaphthoquinones 346 in excellent yields and enantioselectivity (up to 99% yield and 97% ee, Scheme 58b). 242 The utilization of a newly designed BOCp ligand proved essential to the excellent enantioselective control. A further mechanistic study showed that the reaction initializes from the C−H bond activation of benzo[h]quinolines 345, followed by the formation of Rh carbene 349.…”

Twofold C−H Activation‐Based Enantio‐ and Diastereoselective C−H Arylation Using Diarylacetylenes as Rare Arylating Reagents

“…transformation of arenes using heteroarenes as an arylating reagent. [12] Despite the progress,generation of axial chirality calls for employment of more readily available arylating reagents. Since 1-naphthyl groups represent at ypical bulky aryl ring, formation of 1-naphthyls offers ac onvenient approach to biaryl synthesis.I nt his context, Wang [13] reported in 2019 Satoh-Miura type [14] 1:2a nnulation between amides and alkynes for atroposelective synthesis of naphthalenes (Scheme 1a), where the alkyne contributes four carbon atoms to the naththalene ring (Type I coupling), and the axis preexists in the arene substrate,w hich amounts to dinamic kinetic transformation of the arene substrate.O nt he other hand, alternative role of alkynes may be invoked in ad ifferent chemoselectivity (Scheme 1b, Type II reaction) where the chiral axis is newly constructed.…”