Intramolecular C–H Functionalization of α-Alkyl-α-diazoesters toward the Synthesis of Lactones

Intramolecular C–H functionalization was achieved using rhodium catalysis with α-alkyl-α-diazoesters. Dirhodium tetratriphenylacetate (Rh 2 (TPA) 4 ), a sterically bulky achiral catalyst, was found to enable the formation of lactones. Alkyl γ-lactones were synthesized in excellent yields and diastereoselectivity, and a diverse array of disubstituted lactones (γ, δ, and ε) were synthesized with good yields and diastereoselectivity. This chemistry was extended to intramolecular C–H insertion in late-stage functionalization with excellent regio- and diastereoselectivity.