New Synthetic Processes for the Utilization of Carbon Monoxide as Carbon Resource

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Carbon monoxide is a cheap and abundant feedstock and the development of new synthetic processes to synthesize basically important chemical products utilizing carbon monoxide is highly desirable. We focused on the new process to prepare carboxylic acid derivatives which does not require any transition metal catalysts. Using irradiation conditions, we found mat alkyl iodides react with carbon monoxide in the presence of amines to give good yields of amides. Similarly, in the presence of alcohols, esters were obtained in good yields. The role of photo-irradiation is the homolysis of carbon-iodine bond of alkyl iodide, and the resulting alkyl radical undergoes addition to carbon monoxide to form acyl radicals, which-then abstract iodine from alkyl iodide to form an acyl iodide, thus creating radical chain. We found that thermal initiation system, instead of irradiation, also led to the formation of amides and esters. Ionic quench of acyl iodides by aminolysts and alcoholysis are found to be crucial in. The basic principle was applied for the synthesis of heterocyclic rings having a carbonyl moiety in the ring. Such examples include synthesis of five to seven-membered ring lactones and precursors for nitrogen-heterocycles. New reaction processes incorporating two and three molecules of CO were also achieved with the aid of accelerating effect of palladium catalyst. In summary, through these achievements we developed new processes for the utilization of carbon monoxide in synthesis.