Synthesis of Triafulvalene Precursors by 'Carbene-Dimerization' of 1-Halogeno-1-lithiocyclopropanes

Article abstract of DOI:10.1002/hlca.19970800712

Bi(cyclopropylidenes) 7a, 7c, and 7e are available in a simple one-pot reaction by treating 1,1-dibromocyclopropanes 5 at -95° with BuLi and CuCl₂. Attempts towards triafulvalene precursors with good leaving groups are reported. The most promising attempt makes use of 2,2′-bis(phenylthio)-3.3′-bis(trimethylsilyl)-1.1′- bi(cyclopropylidene) (7c) which has been oxidized to give the bis(phenylsulfonyl) derivative 7g. So far, F^--induced elimination experiments with 7g failed.