Iridium(III)-vinylidene chemistry: Conversion of an iridacyclopentadiene-chlorido complex and terminal alkynes to iridacyclopentadiene-vinyl complexes

摘要

The reactions of [kappa(2)(C-1, C-4)-CR=CRCR=CR](PPh3)(2)Ir(Cl) (9, R=CO2Me) with propargyl alcohol derivatives (2-propyn-1-ol, 2-methyl-3-butyn-2-ol, 1-ethynylcyclopentanol, and 1-ethynylcyclooctanol), in the presence of water leads to the formation of iridium(III)-vinyl complexes bearing the general structure [kappa(2)(C-1, C-4)-CR=CRCR=CR](PPh3)(2)Ir(CO)(kappa(1)-vinyl) where vinyl =- CH=CH2, (E)-CH=CHMe, -CH=C(CH2)(4), or -CH=C(CH2)(7). In these, the CO ligand was derived from the terminal carbon of the starting alkyne and the oxygen atom from water. Under anhydrous conditions, 9 undergoes reaction with 2-propyn-1-ol to give trimethyl 1,3-dihydro-3-oxo-4,5,6-isobenzofurantricarboxylate, the result of a cycloaromatization/transesteri. cation involving the buta-1,3-dien1,4-diyl ligand in 9 and 2-propyn-1-ol. (c) 2007 Elsevier B.V. All rights reserved.