Olefinic-ester cyclizations using Takai–Utimoto reduced titanium alkylidenes

The scope and limitations of the Takai–Utimoto reagent to induce the cyclization of olefinic-esters is described. Critical is the steric environment about both the ester and the olefin. Mechanistically, these results support the hypothesis that cyclized product comes from an olefin metathesis, carbonyl-olefination sequence.