Coupling reactions. 20. Synthesis of functionalized bi(cyclopropylidenes)

In view of the synthesis of attractive triafulvalene precursors 9, a series of bi(cyclopropylidenes) 8 with vinyl-(8a), alkoxycarbonyl (8c -f), hydrox ymethyl (8h), as well as protected hydroxymethyl groups (8g, 8i) have been prepared by simple one-pot reactions of the corresponding 1,2-dibromo-cyclo propanes 6 with BuLi/CuCl2 at -95 degrees. First experiments towards a dire ct low-temperature synthesis of bi(cyclopropylidenes) bearing good leaving groups 9k (X = AcO) and 91 (X = Br) are reported.