Coinage metal complexes with N-heterocyclic carbene ligands as selective catalysts in diboration reaction

We describe the improved catalytic reactivity of terminal alkenes with 1,2-diboranes in the presence of Au(I) and Ag(I) complexes when N-heterocyclic carbene ligands are used. The new catalytic systems are able to diminish the undesired beta-H-elimination of the alkylboryl-metal intermediates, which leads to the formation of hydroborated byproducts. The electronic properties and the molecular structure of the precursors of the catalysts could explain the modest asymmetric induction provided. (c) 2006 Elsevier Ltd. All rights reserved.