Ti-Catalyzed Synthesis of Indolines

Significance

Reported is a titanocene(III) chloride catalyzed radical annulation to form indolines and azaindolines via a reductive cyclization of epoxides tethered to substituted anilines and amino-pyridines. In situ prepared titanocene(III) chloride was used to generate reactive radical intermediates from the epoxide. From the range of substituents investigated, alkyl-substituted substrates afforded modest to good yields, electron-rich substrates gave low yields and electron-deficient substrates afforded the cyclized product in good yields.