Recent Advances in Ligand-Controlled Regio- or Stereodivergent Transition-Metal-Catalyzed Hydroelementation (H[E]) (E = H, B, Si, Ge) of C–C Unsaturated Systems

Abstract

Reductive functionalization of C-C unsaturated systems including alkenes and alkynes with a range of hydroelements (H[E]) is one of the most fundamental, but highly practical methods in the synthesis of functionalized hydrocarbons. Since the resultant hydrocarbon products have strong applicability as a synthetic intermediate, numerous homogeneous orano(metallic) catalysts have been intensively practiced up to date for the reductive functionalization reactions. In particular, well-defined transition metal-based catalysts capable of controlling the product’s regio- or stereoselectivity by harnessing the addition of H[E] into the Cα-Cβ unsaturated bonds, have drawn special attention. In this Review, we describe the recent examples of transition metal catalytic systems (M = Fe, Co, Rh, Pd, Ni) for regio- or stereodivergent hydroelementation reactions (E = H, B, Si, Ge) of (conjugated) alkenes, alkynes, and allenes to give a pair of isomeric products in high selectivities from the same starting compounds simply by depending on ligand variation. The mechanistic aspects on the ligand-controlled selectivity divergence are discussed in detail on the basis of experimental observations and/or computational insights.