Visible-Light-Mediated Catalyst-Free [2+2] Cycloaddition Reaction for Dihydrocyclobuta[<i>b</i>]naphthalene-3,8-diones Synthesis under Mild Conditions oleh Hong-Bo Tan, Jia-Ying Zhou, Ying-Shan Liu, Tong Lei, Shi-Yu Wang, Shuang-Shuang Hu, Xu Zhang, Zhi-Gang Xu, Dian-Yong Tang, Zhong-Zhu Chen, Bo-Chu Wang