Merging Regiodivergent Catalysis with Atom‐Economical Radical Arylation

A titanocene‐catalyzed regiodivergent radical arylation is described that allows access to either enantiomerically pure tetrahydroquinolines or indolines from a common starting material. The regioselectivity of epoxide opening that results in the high selectivity of heterocycle formation is controlled by two factors, the absolute configuration of the enantiopure ligands of the (C5H4R)2TiX2 catalyst and the inorganic ligand X (X=Cl, OTs). The overall reaction is atom‐economical and constitutes a radical Friedel–Crafts alkylation.
Indolines and tetrahydroquinolines are formed from the same substrates by titanocene catalysis. The absolute configuration of the cyclopentadienyl ligand and the inorganic ligand determine the regioselectivity of the ring opening and diastereoselectivity of tje radical arylation in the regiodivergent radical arylation of epoxides.