Nickel‐catalyzed coupling of CO 2 and amines: improved synthesis of carbamates

The electrochemical incorporation of carbon dioxide into amines catalyzed by an electrogenerated Ni complex afforded carbamates in moderate yields under very mild conditions ( p   CO   2= 1 atm, room temperature) without any addition of probases. Mechanistic and electrochemical studies revealed the role of reduced nickel species in the activation of CO 2 and electrogenerated CO $_{2}^{.-}$ as a base in the synthesis of carbamates. The influence of number of faradays per mole of amine supplied to the electrodes ( Q ), cathode materials, temperatures, supporting salts and amounts of catalyst was studied to optimize the electrolytic conditions. A plausible reaction mechanism for the reduction of CO 2 was proposed. Copyright © 2007 John Wiley & Sons, Ltd.