Rapid access to phenanthrene-based fused lactones via C(sp3)–H bond functionalization initiated triple ring construction

Abstract

We report the formation of phenanthrene-based fused lactone derivatives based on C(sp³)–H bond functionalization initiated triple ring construction. Employing a stoichiometric amount of Bi(OTf)₃ was the key to the success of the present reaction. The reaction was stopped in the double ring construction under catalytic conditions. A detailed examination suggested that selecting an alkyl group adjacent to a methoxy group was critical to achieving the third cyclization (lactonization).