Olefin epoxidation with inorganic peroxides. Solutions to four long-standing controversies on the mechanism of oxygen transfer.

Four controversies on the mechanism of the olefin epoxidation with Mimoun-type complexes, [MoO(O2)2(OPR3)], Herrmann-type complexes, [ReO(O2)2Me], and related inorganic peroxides have inspired industrial and academic researchers in the last three decades. First, is the oxygen transfer from the peroxo complex to the olefin concerted or stepwise? Second, does the oxidant act as an electrophile or a nucleophile? Third, is the mechanism of the stoichiometric reaction also valid for catalytic protocols? Fourth, how can stereochemical information be transferred between oxidant and substrate? In this Account, we discuss answers to the long-standing questions, focusing on recent contributions from quantum chemical calculations.