Synthesis of electronically modified Ru-based neutral 16 VE allenylidene olefin metathesis precatalysts

Electronic modifications within Ru-based olefin metathesis precatalysts have provided a number of new complexes with significant differences in reactivity profiles. So far, this aspect has not been studied for neutral 16 VE allenylidenes. The first synthesis of electronically altered complexes of this type is reported. Following the classical dehydration approach (vide infra) modified propargyl alcohols were transformed to the targeted allenylidene systems in the presence of PCy?. The catalytic performance was investigated in RCM reaction (ring closing metathesis) of benchmark substrates such as diallyltosylamide and diethyl diallylmalonate.