The Thermal [2+2] Cycloaddition of 1-Halo-2-(9-fluorenylidene)ethylene to Afford Fluorene-9-spiro-1′-[2′-halo-3′-(9-fluorenylidene)-4′-halomethylene]cyclobutane
The Thermal [2+2] Cycloaddition of 1-Halo-2-(9-fluorenylidene)ethylene to Afford Fluorene-9-spiro-1′-[2′-halo-3′-(9-fluorenylidene)-4′-halomethylene]cyclobutane