Synthesis of 7H-Benzo[e]naphtho[1,8-bc]silines by Rhodium-catalyzed [2+2+2] Cycloaddition

An efficient synthesis of 7H-benzo[e]naphtho[1,8-bc]silines has been developed by a rhodium-catalyzed [2 + 2 + 2] cycloaddition of alkynyl(8-alkynyl-1-naphthyl)silanes with internal alkynes. High chemoselectivity can be realized by employing P(2-MeOC6H4)(3) as the ligand for rhodium. Preliminary investigation of its asymmetric variant has also been described to create a silicon stereogenic center with relatively high enantioselectivity.