Double Strain-Release (3+3)-Cycloaddition: Lewis Acid Catalyzed Reaction of Bicyclobutane Carboxylates and Aziridines.

A (3+3)-cycloaddition to afford 2-azabiyclo[3.1.1]heptanes was realized by reacting highly strained aryl bicyclo[1.

GaCl-Mediated Cascade [2 + 4]-Cycloaddition/[4 + 2]-Annulation of Donor-Acceptor Cyclopropanes with Conjugated Dienes: Strategy for the Construction of Benzobicyclo[3.3.1]nonane Skeleton.

Structurally important benzobicyclo[3.3.1]nonane derivatives were synthesized by a gallium trichloride mediated reaction of readily available donor-acceptor cyclopropanes (DACs) with 1,3-dienes as a one-pot cascade ionic [2 + 4]-cycloaddition/Friedel-Crafts-type cyclization process.