Ring‐Opening Reactions of Epoxides With Titanium(III) Reagents

The ring‐opening reactions of epoxides with titanium(III) reagents such as Cp 2 TiCl are critically reviewed, including the scope, limitations, and mechanism of these synthetically useful transformations. The initial reaction proceeds by single‐electron transfer to give a carbon‐centered β‐titanoxy radical. The resulting radical can be terminated by a number of different reaction pathways, including epoxide deoxygenation, reduction to the alcohol, intermolecular addition to activated olefins, and intramolecular addition (cyclization). The literature is surveyed from the first reported examples in 1988 through October, 2021.