Synthesis of Benzo[b][1,4]oxazine-3(4H)-thione Derivatives and Their Anti-tyrosinase Activity

To investigate whether a “β-phenyl-α,β-unsaturated thiocarbonyl” scaffold can play a key role in tyrosinase inhibition, benzo[b][1,4]oxazine-3(4H)-thione derivatives bearing the scaffold were synthesized through a three-step reaction including Knoevenagel condensation. Four compounds showed not only high binding affinity with tyrosinase on docking simulation but also greater inhibitory activity against mushroom tyrosinase than arbutin. These results indicate that a “β- phenyl-α,β-unsaturated thiocarbonyl” may serve as an important chemical scaffold for potent tyrosinase inhibitors.