Cu(i) catalysis for selective condensation/bicycloaromatization of two different arylalkynes: direct and general construction of functionalized C–N axial biaryl compounds

Abstract

Selective condensation/bicycloaromatization of two different arylalkynes is firstly developed under ligand-free copper(i)-catalysis, which allows the direct synthesis of C–N axial biaryl compounds in high yields with excellent selectivity and functional group tolerance.

Copper–Catalyzed Construction of the Indole Core: Recent Advancements

“…[61] The reaction involved Cu(OAc) 2 -promoted intramolecular cyclization followed by further indolylation in hexafluoroisopropanol (HFIP) solvent ( Scheme CuI-mediated assembly of o-alkynylanilines 27 with oacetylaryl alkynes 28 to afford 1,1'-naphthylindoles 29 was demonstrated by Zhou's group. [62] This is an important example of step-economic synthesis of CÀ N axial biaryl compounds via selective condensation/bicycloaromatization of two different arylalkynes (Scheme 10). Notably, the coupled five-six aromatic rings were generated through the selective formation of two C(sp Oxidative cyclization of o-alkynylanilines 30 could be performed via copper catalyzed radical approach to obtain 2hydroxy-2-aryl indol-3-ones 31.…”

Exploiting the reactivities ofortho-alkynyl aryl ketones: opportunities in designing catalytic annulation reactions

“…Zhou and co-workers found that the Cu( i )-catalyzed reaction worked efficiently in the presence of Cs 2 CO 3 in HFIP, allowing a direct formation of key intermediate imine Int40-3 by dehydration. 78 This intermediate then undergoes both 6- endo-dig carbocyclization and 5- endo-dig aza-cyclization to C–N axial biaryl compounds.…”

Tunable Regio- and Stereoselective Synthesis of Z-Acrylonitrile Indoles and 3-Cyanoquinolines from 2-Alkynylanilines and Alkynylnitriles

“…Tang et al documented the formation of N -indolyl or N -benzofuranyl indole scaffolds via Cu-catalyzed tandem cyclization of o -alkynylanilines with cyclohexadienimines or cyclohexadienones, respectively, in the presence of 1,2-DCE (Scheme c) . Recently, Zhou et al proposed a Cu-catalyzed strategy in HFIP for the construction of C–N axial biaryl compounds using o -amino and o -carbonyl aryl alkynes (Scheme d) . In addition to alkynes, 2-alkynylanilines have shown good reactivity with nitriles as well.…”

“…8 Recently, Zhou et al proposed a Cu-catalyzed strategy in HFIP for the construction of C−N axial biaryl compounds using o-amino and o-carbonyl aryl alkynes (Scheme 1d). 9 In addition to alkynes, 2-alkynylanilines have shown good reactivity with nitriles as well. Wang et al documented a BF 3 •Et 2 O promoted synthesis of 4-amido cinnolines using a diazotization and cyclization sequence of o-alkynylanilines in the presence of t-BuONO (TBN) (Scheme 1e).…”