Visible light enhanced dearomative [2+2] cycloaddition of simple heterocycles

The ambition to produce complex molecules from simple precursors is a growing demand in various fields such as the pharmaceutical industry. Visible – light promoted dearomative cycloadditions achieve this goal in a green and sustainable way, becoming increasingly popular in this area. These reactions can follow two paths: the arene’s activation or the arenophile’s activation. The first pathway has been extensively explored in literature, with Dhar’s group1 and Glorius’ group2 presenting two different methods to dearomatize benzoheterocycles in 2020 and 2019, respectively, leading to a lack of knowledge regarding the second activation route. This project is focused on the activation of the arenophile partner. This activation of a cinnamyl unit via energy transfer paves the way to the dearomative [2+2] cycloaddition of (benzo)heterocycles.Notably, the reaction proposed allows the formation of a fused tricyclic structure with complete atom economy under mild conditions, using a low photocatalyst loading, a readlilyavailable binaphthyl co-catalyst3 , and a cheap light source; this approach opens new opportunities in the design of complex molecules for pharmaceutical applications. [1] Martins S. Oderinde, T. G. Murali Dhar, Et Al., J. Am. Chem., 2020, 6, 3094 [2] F. Strieth-Kalthoff, F. Glorius, Et Al. Approah, Chem, 2019, 5, 2183 [3] Hoch, M., Sparascio, S., Cerveri, A. et al. . Photochem Photobiol Sci 23, 1543)