Direct observation of a thermal ring-walk rearrangement in a spironorcaradiene system

Abstract

At 100 "C in toluene, cis-2'-trifluoromethylspiro [acenaphthene-1,7'-norcaradiene]-2-0ne (1 ; X = CF,) interconverts with its 3'-trifluoromethyl-~ubstituted isomer (2; X = CF,), this being the first directly observed example of a degenerate ring-walk rearrangement for a norcaradiene with a spiro-ring system attached a t C-7.

Donor–acceptor accelerated norbornadiene rearrangements

“…The implied easier rearrangement of 3h than of 3c agrees * Walk rearrangement of norcaradienes has been observed at 100 "C (ref. 12).…”