Regioselective Carbonylation of trans-Disubstituted Epoxides to β‑Lactones: A Viable Entry into syn-Aldol-Type Products

Two new catalysts are reported for the regioselective carbonylation of trans-disubstituted epoxides to cis-β-lactones. The two catalysts display high and opposing selectivities, which generally are difficult to achieve for this class of epoxides. The resulting β-lactones are well-defined precursors for a wide variety of aldol-type compounds. Altogether, carbonylation of disubstituted epoxides is established as a viable and economical entry into syn- and anti-aldol products.