[2+2+2] cocyclotrimerization with ferrocenylalkynes

Cocyclotrimerization of ferrocenylalkynes FcCdropCR (R = H and CH2OH) with alpha,omega-diynes X(CH(2)CdropCH)(2), where X = O, C(CO2Et), C(CN)(CO2Et), C(COMe)(2), and C(COMe)(CO2Et), to give functionalised ferrocenylarenes was attempted in the presence of various catalytic systems: [RhCl(PPh3)(3)], [CoBr(PPh3)(3)], [NiBr2(dppe)]/Zn, [(Ir(cod)Cl)(2)]/dppe and [CpCo(cod)]/PPh3 [Cp = eta(5)-cyclopentadienyl, cod = eta(4)-cyclo-octa-1,5-diene, and dppe = 1,2-bis(diphenylphosphanyl)ethane]. The results indicate that Wilkinson's catalyst effects the cocyclotrimerization to afford the respective ferrocenylarenes in good yields and under mild conditions regardless of the nature of the functional groups. ((C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003).