Synthesis Of Complex Hexacyclic Compounds Via A Tandem Rh(Ii)-Catalyzed Double-Cyclopropanation/Cope Rearrangement/Diels-Alder Reaction

Treatment of (E)-1-(methoxymethylene)-1,2,3,4-tetrahydronaphthalene with styryl diazoacetates in the presence of catalytic amounts of the dirhodium complex Rh-2(S-DOSP)(4) provides a highly enantioenriched hexacyclic product with 10 new stereogenic centers. The transformation proceeds by a cascade sequence starting with a double cyclopropanation of a benzene ring, followed by a Cope rearrangement of a divinylcyclopropane and then an intramolecular Diels-Alder cycloaddition.