TY - JOUR
T1 - Cobalt Catalyzed Z -Selective Hydroboration of Terminal Alkynes and Elucidation of the Origin of Selectivity
AU - Obligacion, Jennifer V.
AU - Neely, Jamie M.
AU - Yazdani, Aliza N.
AU - Pappas, Iraklis
AU - Chirik, Paul J.
PY - 2015/5/13
Y1 - 2015/5/13
N2 - A bis(imino)pyridine cobalt-catalyzed hydroboration of terminal alkynes with HBPin (Pin = pinacolate) with high yield and (Z)-selectivity for synthetically valuable vinylboronate esters is described. Deuterium labeling studies, stoichiometric experiments, and isolation of catalytically relevant intermediates support a mechanism involving selective insertion of an alkynylboronate ester into a Co-H bond, a pathway distinct from known precious metal catalysts where metal vinylidene intermediates have been proposed to account for the observed (Z) selectivity. The identity of the imine substituents dictates the relative rates of activation of the cobalt precatalyst with HBPin or the terminal alkyne and, as a consequence, is responsible for the stereochemical outcome of the catalytic reaction.
AB - A bis(imino)pyridine cobalt-catalyzed hydroboration of terminal alkynes with HBPin (Pin = pinacolate) with high yield and (Z)-selectivity for synthetically valuable vinylboronate esters is described. Deuterium labeling studies, stoichiometric experiments, and isolation of catalytically relevant intermediates support a mechanism involving selective insertion of an alkynylboronate ester into a Co-H bond, a pathway distinct from known precious metal catalysts where metal vinylidene intermediates have been proposed to account for the observed (Z) selectivity. The identity of the imine substituents dictates the relative rates of activation of the cobalt precatalyst with HBPin or the terminal alkyne and, as a consequence, is responsible for the stereochemical outcome of the catalytic reaction.
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U2 - 10.1021/jacs.5b00936
DO - 10.1021/jacs.5b00936
M3 - Article
C2 - 25884604
AN - SCOPUS:84929377738
VL - 137
SP - 5855
EP - 5858
JO - Journal of the American Chemical Society
JF - Journal of the American Chemical Society
SN - 0002-7863
IS - 18
ER -