Synthesis of Lactones via C-H Functionalization of Nonactivated C(sp)-H Bonds.

An electron-deficient amide is utilized as a directing group to functionalize nonactivated C(sp)-H bonds through radical 1,5-hydrogen abstraction. The γ-bromoamides formed are subsequently converted to γ-lactones under mild conditions. The method described is not limited to tertiary and secondary positions but also allows functionalization of primary nonactivated sp-hybridized positions in a one-pot sequence. In addition, the broad functional group tolerance renders this method suitable for the late-stage introduction of γ-lactones into complex carbon frameworks.