Acid and Base Promoted Rearrangements of Hexacyclo(11.2.1.02,12.05,10. 05,15.010,14)hexadeca-6,8-diene-4,11-dione

Abstract Hexacyclo[11.2.1.02,12.05,10.05,15.010,14]hexadeca-6,8-diene-4,11-dione (3) was synthesized via ring-expansion of hexacyclo[10.2.1.02,11.04,9.04,14.09,13]pentadeca-5,7-diene-3,10-dione (1). Reaction of a toluene solution of 3 with a catalytic amount of HCl resulted in extensive skeletal rearrangement, thereby affording 6,7-benzotetracyclo[7.3.0.04,12.05,10]dodecane-2,6-dione (4). Subsequent reaction of 4 with 3,6-diphenyl-1,2,4,5-tetrazine (5) afforded a novel molecular cleft, 6. Compound 3 reacted smoothly with ethanolic KOH at ambient temperature (in 3 h) or at reflux (in 0.5 h) to afford a rearranged product, 7. The structures of 3, 4, 5, and 7 were established unequivocally via application of single crystal X-ray crystallographic methods.