A mild and general route for preparing 2-pyrones from CO2 and diynes is described. Under only 1 atm of CO2, excellent yields of pyrone are obtained using catalytic amounts of Ni(COD)2 and imidazolylidene ligand, IPr. In addition, stoichiometric reactions between the isolated complex Ni(IPr)2, diynes, and CO2 suggest that the pathway involves initial reaction with CO2 as the key step.

We incorrectly assigned the regiochemistry of pyrone 25. X-ray analysis revealed that the TMS group is at the 3-position rather than the 6-position. The correct structure is shown here: JA046854R

Pyran derivatives Pyran derivatives R 0340Efficient Nickel-Catalyzed [2 + 2 + 2] Cycloaddition of CO 2 and Diynes. -A new method to synthesize substituted pyrones is presented. The nickel-catalyzed cycloaddition reaction employs catalytic amounts of Ni (0) and the imidazol-2-ylidene ligand, atmospheric pressure of CO 2 and mild reaction conditions. -(LOUIE*, J.; GIBBY, J. E.; FARNWORTH, M. V.; TEKAVEC, T. N.; J.