Manganese porphyrin-mediated aerobic epoxidation of propylene with isoprene: A new strategy for simultaneously preparing propylene epoxide and isoprene monoxide

The direct epoxidation of propylene by O2 is a significant and challenging topic. The key factor for this homogeneous aerobic epoxidation is the activation of molecular oxygen under mild conditions. In this work, the aerobic epoxidation of propylene catalyzed by manganese porphyrins was achieved in the presence of isoprene. Isoprene contains an allyl methyl group, and the α-H can be easily removed to achieve the activation of molecular oxygen. The conversion of propylene was 38% and the selectivity toward propylene oxide (PO) was up to 87%. The role of isoprene was demonstrated, and a plausible mechanism was proposed. The protocol reported herein is expected to provide a strategy for the simultaneous preparation of propylene oxide and isoprene monoxide.