Synergetic Catalysis for One‐pot Bis‐alkoxycarbonylation of Terminal Alkynes over Pd/Xantphos−Al(OTf)3 Bi‐functional Catalytic System.

Tandem bis‐alkoxycarbonylation of alkynes allows for the preparation of 2‐substituted succinates from alkynes and nucleophile alcohol via two successive alkoxycarbonylation with advantages of 100 % atomic economy and simplified one‐pot operation. Herein, the one‐pot tandem bis‐alkoxycarbonylation of alkynes was accomplished over the bi‐functional catalytic system containing Xantphos‐modified Pd‐complex and Lewis super‐acid of Al(OTf)3. It was found that, via the synergetic catalysis, the involved Xantphos‐modified Pd‐complex was responsible for the activation of CO and the alkynes through coordination to Pd‐center while Al(OTf)3 was in charge of the activation of the alcohol to facilitate the formation of [Pd−H]+ active species. The in situ high‐pressure FT‐IR analysis, coupled with 1H/13C NMR spectral characterizations, confirmed that the introduced Al(OTf)3 with intensive oxophilicity (via acid‐base pair interaction) was able to activate nucleophilic MeOH to be a reliable proton‐donor (i. e. hydride‐source) to warrant the formation and stability of [Pd−H]+ species upon the oxidation of Pd0 by H+ (Pd0+H+→[PdII−H]+). Over the developed bi‐functional catalytic system, the yields of the target diesters were obtained in the range of 36∼86 % in this sequence with the wide substrate scope. [ABSTRACT FROM AUTHOR]