Synthetic approaches to [n](3,5)-troponophanes. Novel rearrangements of 10, 10-dichloro-1,2,6,7,8,9-hexahydro-4a,9a-methano-5H-benzocyyclohepten-2-one

Abstract

On standing the title compound 1c gives an enone isomer 4 and the heptacyclic compound 5; the formation of both of these products has been rationalised in terms of the intermediacy of the bridged tropylium ion 8 and 13C-labelling studies support this proposal.