C-C and C-O Coupling Reactions of Terminal Alkynes by a Water Soluble Organoiridium Electron-transfer Mediator in Thin Layer of Water on Gold Electrode

Abstract

2+ was previously reported [38].Since it is well-known that terminal alkynes can be activated by organoiridium compounds [11][12][13][14][15][16][17][18], this voltammetric observation prompted us to look into details of reduced-metal catalyzed activation of alkynes in biphasic (H 2 O/CH 2 ClCH 2 Cl) solution. The biphasic AbstractAn electrochemical reduction process is described for the rapid and efficient conversion of terminal alkynes into useful products. Terminal alkynes (HC≡CR; R = C 6 H 5 , p-C 6 H 4 CH 3 , CH 2 C 6 H 5 , C 6 H 9 ) were hydrated and dimerized by cathodic reduction of catalytic amount (5 %) of [Cp * Ir(NCMe) 2 (PAr 3 )](OTf) 2 , 1, (E pc = −620 mV vs Ag/AgCl) through an aqueous/nonaqueous interface. Thin aqueous layer containing water-soluble compound 1 was formed on gold electrode. The cathodic reduction current height of 1 increases as increasing the concentration of terminal alkynes. The electrolysis of 1 while contacting with terminal alkynes containing organic solvent produced ketones, aldehydes and dimerized enyne products from terminal alkyne/water reaction systems. A new micro-scale electrocatalysis technique is depicted.