Gold‐Catalyzed Oxidative Ring Expansions and Ring Cleavages of Alkynylcyclopropanes by Intermolecular Reactions Oxidized by Diphenylsulfoxide

A golden opportunity: A novel gold-catalyzed oxidative ring-expansion of unactivated cyclopropylalkynes using Ph2SO has been developed (see scheme). For substrates bearing a donor group at the cyclopropane ring, preliminary results reveal a distinct cleavage of the cyclopropane unit; such a ring cleavage is further applicable to the synthesis of 2H-pyrans. L=P(tBu)2(o-biphenyl), Tf=triflate.