An isolable but highly reactive o-quinodimethane; 1,1a,2,3,4,4a-hexahydro-9,10-diphenyl-1,4-methanoanthracene

Abstract

The relatively stable o-quinodimethane 7 has been prepared by photodecarbonylation of the 1,3-diphenylinden-2-one-norbornene adduct 5. Reactions of 7 with phenyltriazolinedione, sulphur dioxide and triplet oxygen all occur to the less hindered face of the diene system terminating at the α,α′-positions of the o-quinodimethane. The same face of the same diene system is involved in forming the major carbonyl iron complex, 12, of 7. Both thermolysis and acid-catalysed rearrangement of 7 give the dihydronaphthalene 10. The 1,5-sigmatropic hydrogen shift of 7 that would give 10 is slow at 140 °C.