reactions involving nickel‐catalyzed additions of (hetero)arylboronic acids to alkynes, followed by cyclization of the alkenylnickel intermediates onto tethered acyclic ketones to give chiral tertiary‐alcohol‐containing products in high enantioselectivities, are described. The reversible E/Z isomerization of the alkenylnickel intermediates enables overall anti‐arylmetallative cyclization to occur. The ring
Visible-light induced metal-free intramolecular reductive cyclisations of ketones with alkynes and allenes
作者:Nana Tang、Raphael J. Zachmann、Hui Xie、Jun Zheng、Bernhard Breit
DOI:10.1039/d2cc06972e
日期:——
visible-light-induced, intramolecular, reductive cyclisation of ketones with an unsaturated hydrocarbon moiety was developed. In contrast to conventional protocols requiring resource precious or hazardous metal sources, this method enables facile access to ketyl radicals under metal-free and mild reaction conditions. By polarity-reversed, ketyl radical hydroalkoxylation of alkynes and allenes, a variety of
The intramolecular Pauson-Khand reaction of various 2-aryl-1-hepten-6-ynes and its aza-derivatives (exo-olefins) efficiently produced arylbicyclo[3.3.0]octenones and azaoctenone bearing quaternary carbon centers at angular positions in good yields. Although a similar reaction of 2-phenyl-1-octen-7-yne (exo-olefin), which is a homologue of 2-phenyl-1-hepten-6-yne, did not take place, the reaction of the methyl derivatives smoothly proceeded. However, the reaction of regioisomeric 1-phenyl-1-octen-7-yne (endo-olefin) afforded the desired product in moderate yields.