Metathesis of Classical and Functionalized Olefins Catalyzed by Silica-Supported Single-Site Well-Defined W and Mo Pre-catalysts

Abstract

Olefin metathesis of α-olefins (C6, C8, C10), α, β-unsaturated ester, α, β- unsaturated acetate and cross-metathesis of 1-octene and ethyl 6-heptenoate were carried out using well-defined [(≡Si−O−)W(CH3)5] and [(≡Si−O−)Mo(≡CtBu)(CH2tBu)2] pre-catalysts. During the reaction, it was observed that irrespective of the chain length, linear α-olefins are almost showing similar TON. We observed that Mo pre-catalyst performs better with TONs between 700 and 1478 as compared to W with TONs between 213 and 962 at room temperature. Both pre-catalysts performed equally at 70 °C, with almost similar activity as well as TON (≈1700). We also carried out self-metathesis of functionalized olefins using both silica-supported W and Mo pre-catalysts. It was observed that W pre-catalyst performs much better than Mo pre-catalyst for functionalized olefin metathesis reaction in our conditions. Additionally, we noticed that W pre-catalyst provides selective metathesis product, whereas Mo pre-catalyst gives a range of products due to the isomerization of the olefinic bond.