Efficient and Recyclable RuCl ⋅ 3HO Catalyst Modified with Ionic Diphosphine for the Alkoxycarbonylation of Aryl Halides.

A series of ionic (mono-/di-)phosphines (, , and ) with structural similarity and their corresponding neutral counterparts (, , and ) were applied to modulate the catalytic performance of RuCl ⋅ 3HO. With the involvement of the ionic diphosphine (), in which the two phosphino-fragments were linked by butylene group, RuCl ⋅ 3HO with advantages of low cost, robustness, and good availability was found to be an efficient and recyclable catalyst for the alkoxycarbonylation of aryl halides. The -based RuCl ⋅ 3HO system corresponded to the best conversion of PhI (96 %) along with 99 % selectivity to the target product of methyl benzoate as well as the good generality to alkoxycarbonylation of different aryl halides (ArX, X=I and Br) with alcohols MeOH, EtOH, -PrOH and -BuOH. The electronic and steric effects of the applied phosphines, which were analyzed by the P NMR for measurement and single-crystal X-ray diffraction, were carefully co-related to the performance RuCl ⋅ 3HO catalyst. In addition, the -based RuCl ⋅ 3HO system could be recycled successfully for at least eight runs in the ionic liquid [Bmim]PF.