C–H insertions in oxidative gold catalysis: synthesis of polycyclic 2H-pyran-3(6H)-ones via a relay strategy

A new application of oxidatively generated, highly electrophilic α-oxo gold carbenes in synthetically streamlining insertions into unactivated C–H bonds is realized by converting them to putative vinyl cation intermediates in a relay approach. This chemistry permits expedient access to cyclic dihydropyran-3-ones.