Cyclopropanation with gold(I) carbenes by retro-Buchner reaction from cycloheptatrienes

Aryl- or styrylcycloheptatrienes undergo retro-Buchner reactions with cationic gold(I) complexes such as [2-PhC₆H₄(Me₃C)₂PAuN≡CMe]⁺.bul.SbF^6- to generate gold carbene complexes which cyclopropanate olefins such as trans-stilbene to give di- and trisubstituted cyclopropanes in 39-91% yields and in most cases stereoselectively.