Oxidative Aromatization of 3,4-Dihydroquinolin-2(1 H)-ones to Quinolin-2(1 H)-ones Using Transition-Metal-Activated Persulfate Salts.

Inorganic persulfate salts were identified as efficient reagents for the oxidative aromatization of 3,4-dihydroquinolin-2(1 H)-ones through the activation of readily available transition metals, such as iron and copper. The feasible protocol conforming to the requirement of green chemistry was utilized in the preparation of the key intermediate (7-(4-chlorobutoxy)quinolin-2(1 H)-one 2) of brexpiprazole in 80% isolated yield on a 100 g scale, and different quinolin-2(1 H)-one derivatives with various functional groups were demonstrated in 52-89% yields.