Unexpected coupling reaction of 9-lithiobromomethylene-9H-fluorene with 6,6-dicyclopropylfulvene

Article abstract of DOI:10.1055/s-1997-4505

Metallation of 9-bis(bromomethylene)-9H-fluorene with one equivalent of BuLi at -78°C followed by quenching with 6,6-dicyclopropylfulvene and subsequent warming (room temperature, 18 h) gave an adduct identified as compound 5 (~ 70% yield). Under identical conditions dimethylfulvene and cyclopropylmethylfulvene failed to give a similar adduct. Simple and efficient syntheses of 9-bromomethylene- and 9-bis(bromomethylene)-9H- fluorene are also described.