Stereoselective Synthesis of Highly Functionalized Indanes and Dibenzocycloheptadienes through Complex Radical Cascade Reactions

Two highly stereoselective radical-mediated syntheses of densely functionalized indanes and dibenzocycloheptadienes from ortho-vinyl- and ortho-vinylaryl-substituted N-(arylsulfonyl)-acrylamides, respectively, are presented here. The chemoselective addition of in situ generated radicals (X(·)) onto the styrene moieties triggers an unprecedented reaction cascade, resulting in the formation of one new C-X bond and two new C-C bonds, a formal 1,4-aryl migration, and the extrusion of SO2 to generate an amidyl radical intermediate. This intermediate, upon H abstraction, leads to the observed 5- and 7-membered ring carbocyclic products, respectively, in a highly efficient manner.