Syntheses of 6-8-5 tricyclic ring systems by carbonylative [2+2+1] cycloaddition of bis(allene)s

The synthetic route for the construction of the 6-8-5 tricyclic carbon frameworks has been developed. The [RhCl(CO)dppp]2-catalyzed intramolecular Pauson-Khand-type reaction of the bis(allene)s, derived from dimedone, provided the corresponding bicyclo[6.3.0] skeleton in one operation.