Efficient construction of the oxatricyclo[6.3.1.0(0,0)]dodecane core of komaroviquinone using a cyclization/cycloaddition cascade of a rhodium carbenoid intermediate

The rhodium(II)-catalyzed cyclization/cycloaddition cascade of a o-carbomethoxyaryl diazo dione is described as a potential route to the oxatricyclo[6.3.1.0(0,0)]dodecane substructure of the icetexane diterpene komaroviquinone. The initially formed carbonyl ylide dipole prefers to cyclize to an epoxide at 25 degrees C but can be induced to undergo cycloaddition across the tethered pi-bond at higher temperatures. [reaction: see text]