Construction of tricyclic pyran derivatives through intramolecular [2+2+2] cycloaddition of allenynes with tethered aldehydes

Rh(I)-catalyzed intramolecular [2+2+2] cycloaddition of allenynes with tethered aldehydes was investigated. The cyclizations proceeded smoothly under mild conditions to give various tricyclic compounds containing a pyran ring in good to high yields in a stereoselective manner.