Chiral discrimination of small substituents in biaryl atropisomer construction: enantioselective synthesis of axially chiral 1-azafluorene via Ni-catalyzed [2+2+2] cycloaddition
作者:Jin-Huang Peng、Yu-Qing Zheng、Li-Gang Bai、Wen-Bo Liu
DOI:10.1007/s11426-023-1749-x
日期:2023.11
Construction of axially chiral 1-azafluorenes via nickel-catalyzed [2+2+2] cycloaddition of alkynes and (o-alkynyl)benzyl nitriles is described. This strategy enables enantioselective discrimination of two sterically similar ortho substituents, such as H and F, during the construction of tri-ortho-substituted biaryl atropisomers. Mechanistic studies including the stereochemistry model and the stability
Unprecedented regioselective trans-hydroboration and carboboration of unbiased electronically internal alkynes were realized via a nickel catalysis system with the aid of the directing group strategy. Furthermore, the excellent α- and β-regioselectivity could be accurately switched by the nitrogen ligand (terpy) and phosphine ligand (Xantphos). Mechanistic studies provided an insight into the rational