Rhodium-catalyzed [5+2] cycloadditions of allenes and vinylcyclopropanes: Asymmetric total synthesis of (+)-dictamnol

[GRAPHICS] The asymmetric synthesis of (+)-dictamnol is described, based on the rhodiu m catalyzed [5 + 2] cycloaddition of an allene and vinylcyclopropane. This cycloaddition methodology provides the basis for a general and efficient ro ute to various bicyclo[5.3.0]decenes, ring systems common to a wide range o f natural and designed compounds of structural and medicinal interest.