[2+2+2] Cocyclotrimerization with Ferrocenylalkynes

Cocyclotrimerization of ferrocenylalkynes FcC≡CR (R = H and CH 2 OH) with α,ψ‐diynes X(CH 2 C≡CH) 2 , where X = O, C(CO 2 Et), C(CN)(CO 2 Et), C(COMe) 2 , and C(COMe)(CO 2 Et), to give functionalised ferrocenylarenes was attempted in the presence of various catalytic systems: [RhCl(PPh 3 ) 3 ], [CoBr(PPh 3 ) 3 ], [NiBr 2 (dppe)]/Zn, [{Ir(cod)Cl} 2 ]/dppe and [CpCo(cod)]/PPh 3 [Cp = η 5 ‐cyclopentadienyl, cod = η 4 ‐cycloocta‐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. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)