Novel Ruthenium-Catalyzed Cross-Carbonylation of Alkynes and 2-Norbornenes to Hydroquinones

Unsymmetrically substituted hydroquinones were obtained in high yields by the novel ruthenium-catalyzed cross-carbonylation of alkynes and 2-norbornenes. For example, treatment of 4-octyne and 2-norbornene with 2 mol % Ru 3 (CO) 12 in N-methylpiperidine under 60 atm of carbon monoxide at 140 °C for 20 h gave the corresponding hydroquinone, 4,5-dipropyltricyclo[6.2.1.0 2,7 ]undeca-2(7),3,5-triene-3,6-diol, in 85% yield. The reaction apparently involves a maleoylruthenium intermediate which is generated by the reaction of an alkyne and two molecules of carbon monoxide on the ruthenium.