Replacement reactions of 1,1-dichloro-2,5-diphenylcyclopropabenzene with organometallic reagents

The replacement of the chloro-substituents of 1,1-dichloro-2,5-diphenylcyclopropabenzene (1) can be effected by various organometallic reagents. The products of reaction with Grignard and organolithium reagents and with lithium aluminium hydride have been characterised. Although the gem-diethyl derivative (8) is the only isolated product in which the ring system is retained, spectroscopic evidence is presented which supports the involvement of 1,1-disubstituted cyclopropabenzenes in all the reactions. With methylmagnesium iodide, the cyclopropabenzene (1) suffers the equivalent of Grignard reduction to afford the unanticipated fluorene (25).