Lighting the way: a copper(I)-carbazole-carbene catalyst for [2+2] photocycloaddition of benzofurans

Benzofuran derivatives are widely employed in medicine and pharmacology due to their remarkable biological activities and potential therapeutic applications. However, synthetic strategies toward cyclobutane-fused polycyclic benzofurans have remained largely unexplored. This thesis reports the use of a copper-based photocatalyst for the efficient and straightforward synthesis of cyclobutane-fused polycyclic benzofuran derivatives via a (UV) visible light-mediated [2+2] photocycloaddition reaction. This method offers a new and practical approach to access structurally complex benzofuran frameworks. The newly developed catalyst, [Cu(IPr)Cbz] (IPr= 1,3-bis(2,6-diisopropylphenyl)imidazole-2-ylidene; Cbz= carbazole), proved highly effective in this challenging and important transformation, demonstrating its value as an inexpensive and efficient photocatalytic system.