DBU‐Mediated Isomerization/6‐π Electro‐Cyclization/Oxidation Cascade of Sulfonyl‐Substituted Allenyl Ketones for the Construction of Hetero‐1,3,5‐Trisubstituted Benzene**

Abstract 1,3,5‐tri‐substituted benzene rings emerged with unique properties has widespread applications in materials, boosting the rapid development of their synthesis. Despite the significance, the direct construction of hetero‐1,3,5‐trisubstituted benzene core was far less‐developed. Herein, we realized a DBU‐mediated isomerization/6‐π electro‐cyclization/oxidative aromatization cascade of sulfonyl‐substituted allenyl ketones under an air atmosphere (DBU=1,8‐diazabicyclo[5.4.0]undec‐7‐ene). This versatile protocol featured metal‐free conditions, easy operation, and broad functional group tolerance provides a new avenue for the construction of hetero‐1,3,5‐tri‐substituted benzene.