Tris-Annelated Benzenes Selectively Perfunctionalized on One Side Only: Hexachlorobenzotrinorbornadiene as a Versatile Scaffold for the Construction of Molecular Domes

Well-defined, rigid molecular domes are obtained via substitution of the chlorine atoms of hexachlorobenzotrinorbornadiene syn-3, efficiently synthesized in 1:2 ratio along with its anti-isomer by CuTC-promoted cyclotrimerization of 3-bromo-2-trimethylstannylnorbornadiene 8. The three dichlorovinyl functions at the edge of syn-3 are displaced by sulfur nucleophiles and Grignard reagents with Ni(II)Cl2dppe as catalyst, gaining the persubstituted vinyl sulfides 9 and 10, and persubstituted methyl 12 and phenylethynyl 13.