LReO₃ Epoxidizes, <i>cis</i>-Dihydroxylates, and Cleaves Alkenes as Well as Alkenylates Aldehydes: Toward an Understanding of Why

Abstract

The relative reaction thermodynamics for the probable pathways leading to alkene epoxidation, cis-dihydroxylation, and C−C cleavage as well as alkenylation of aldehydes have been investigated for the reaction of ethylene with LReO3, L = CH3, Cl, OH, OCH3, O-, C5H5(Cp), and C5(CH3)5 (Cp*). We find the reaction pathway exothermicities to be quite sensitive to the ligand. For ClReO3, CH3ReO3, HOReO3, CH3OReO3, and O-ReO3, reaction with ethylene is endothermic with metallaoxetane preferred over dioxylate formation. For CpReO3 and Cp*ReO3, the reaction with ethylene is exothermic but nearly thermoneutral with dioxylate formation preferred. The π-binding attributes of the ligand are found to correlate with thermodyanmic preference.