Oxidative cyclisation of cis- and trans-2,3-dibenzylbutyrolactones using phenyl iodonium bis(trifluoroacetate) and 2,3-dichloro-5,6-dicyano-1,4-benzoquinone

A series of cis- and trans-2,3-dibenzylbutyrolactones have been subjected to oxidative cyclisation using phenyl iodonium bis(trifluoroacetate) and 2,3-dichloro-5,6-dicyano-1,4-benzoquinone. The products obtained include two novel spirodienones 6 and 11, which rearrange with acid to give the dibenzocyclo-octadienes 7, and 12 and 13, respectively.