Directing effects of tethered alkenes in nickel-catalyzed coupling reactions of 1,6-enynes and aldehydes
作者:Ryan M. Moslin、Karen M. Miller、Timothy F. Jamison
DOI:10.1016/j.tet.2006.03.122
日期:2006.8
Nickel-catalyzed reductive coupling reactions of aldehydes and 1,6-enynes proceed in excellent regioselectivity in the absence of a phosphine, and the use of a monodentate phosphine additive leads to the formation of the opposite regioisomer with equally high selectivity. Both products are the result of the same fundamental mechanism, with the inversion of regioselectivity being the result of stereospecific ligand substitution at the metal center. (c) 2006 Elsevier Ltd. All rights reserved.
Ligand-Switchable Directing Effects of Tethered Alkenes in Nickel-Catalyzed Additions to Alkynes
作者:Karen M. Miller、Timothy F. Jamison
DOI:10.1021/ja0446799
日期:2004.12.1
Nickel-catalyzed reductive couplings of aldehydes with alkynes that contain tethered olefins are described, in which the degree and sense of regioselectivity are controlled by the length of the tether and the presence or absence of an additive. When the alkyne and alkene are separated by four bonds, very high (>95:5) regioselectivities are observed. Use of a monodentate phosphine as an additive leads