Vanadium-Catalyzed Synthesis of Geometrically Defined Acyclic Tri- and Tetrasubstituted Olefins from Propargyl Alcohols
作者:Barry M. Trost、Jacob S. Tracy
DOI:10.1021/acscatal.8b04567
日期:2019.2.1
selective formation of geometricallydefined acyclic tri- and tetrasubstituted alkenes from inexpensive and readily available propargyl alcohols is described. Through vanadium oxo catalysis, tri- and tetrasubstituted α-chloro-, bromo-, and iodo-enone olefins can be synthesized with the kinetic E-geometry. Complementary tetrasubstituted β-chloro-, bromo-, and iodo-enone olefins with Z-geometry can be
“Silver Effect” in Gold(I) Catalysis: An Overlooked Important Factor
作者:Dawei Wang、Rong Cai、Sripadh Sharma、James Jirak、Sravan K. Thummanapelli、Novruz G. Akhmedov、Hui Zhang、Xingbo Liu、Jeffrey L. Petersen、Xiaodong Shi
DOI:10.1021/ja303862z
日期:2012.5.30
Clear experimental evidence from X-ray photoelectron spectroscopy and P-31 NMR spectroscopy has been obtained for the first time to confirm that the combination of Ag+ cation with [L-Au](+) results in the formation of different complexes in solution. Re-evaluation of literature-reported gold-catalyzed reactions revealed a significant difference in the reactivities with and without silver. In extreme cases (more than "rare"), the conventional [L-Au](+) catalysts could not promote the reaction without the presence of silver. This investigation has therefore revealed a long-overlooked "silver effect" in gold catalysis and should lead to revision of the actual mechanism.