Synthesis of recyclable tire additives via equilibrium ring-opening metathesis polymerization

Linear <i>trans</i>-polypentenamers are highly desired materials among synthetic tire additives due to their comparable physical properties to natural rubber. <i>trans</i>-Polypentenamer can be prepared by equilibrium ring-opening metathesis polymerization (ROMP) using well-defined ruthenium catalyst systems. This unique feature of the equilibrium polymerization reaction opens a way for the synthesis of durable, environmentally benign elastomers where polymers including synthetic tire additives can be synthesized and readily recycled using the same transition metal catalyst system. The addition of silica fillers significantly improves the physical properties of the composite materials in comparison to the use of polymeric material. It is also known that the structural effects and the polymer–filler surface interaction are of prime importance. Herein, we report on the synthesis of silica filler compatible recyclable polypentenamer copolymers via equilibrium ROMP of cyclopentene <b>1</b> and 4-(triethoxy)­siloxy cyclopentene <b>11</b>. It has been demonstrated that polypentenamer tire additives can be synthesized via equilibrium ROMP affording polymers with high yields (>80%) at 0 °C and can be readily depolymerized at 40 °C and/or under diluted conditions using the same metathesis catalyst systems. Furthermore, the polypentenamer can also be synthesized in neat at room temperature and at very low (10⁵) monomer/catalyst ratio. This methodology is based on the synthesis of polyolefins utilizing a ruthenium-based metathesis catalyst via equilibrium ROMP of cyclopentenes and their silylated derivatives

Enantioselective allylation of α,β-unsaturated aldehydes with allyltrichlorosilane catalyzed by METHOX

α,β-Unsaturated aldehydes 6a-j undergo an enantioselective allylation with allylic trichlorosilanes 2a,b in the presence of METHOX (4) as a Lewis basic catalyst (≤10 mol %) to produce the homoallylic alcohols 7a-l at good to high enantioselectivity (83-96% ee). This study shows that the reactivity scope of METHOX can be extended from aromatic to nonaromatic aldehydes