Practical ruthenium-catalyzed cyclocarbonylation of allenyl alcohols in 2,4,6-collidine leading to alpha,beta-unsaturated lactones: concise stereoselective synthesis of (+)-isomintlactone.

We have found that ruthenium-catalyzed cyclocarbonylation of allenyl alcohols in 2,4,6-collidine under atmospheric pressure of carbon monoxide smoothly proceeds to afford alpha,beta-unsaturated five- and six-membered lactones in moderate to good yields. Furthermore, we have completed a highly stereoselective synthesis of (+)-isomintlactone by the cyclocarbonylation of allenyl alcohol using 2,4,6-collidine.