Notably, the 2o product formed through this method is a key precursor of solifenacin, a competitive cholinergic receptor antagonist. In addition, we tested this method during the late-stage phosgenation reactions of structurally complex pharmaceutical samples. Both of the fluoroquinolone antibiotics, norfloxacin and gatifloxacin, afforded the desired products in high yields and without any detectable side products. When the substrates with nitrogen and oxygen nucleophiles in the same molecule were used, the corresponding cyclic products with inserted carbonyl groups 4-6 were obtained in high yields.