Construction of Three-Dimensional Covalent Organic Frameworks for Photocatalytic Synthesis of 2,3-Dihydrobenzofuran Derivatives

2,3-Dihydrobenzofuran derivatives hold significant value in pharmaceutical and material science due to their prevalence in bioactive molecules and natural products. However, constructing efficient and sustainable catalytic systems for the synthesis of such derivatives remains challenging. Herein, we synthesized two three-dimensional covalent organic frameworks (3D COFs) with donor-acceptor (D-A) units, which enable efficient photocatalytic synthesis of 2,3-dihydrobenzofuran derivatives via oxidative dehydrogenative coupling of alkenyl phenols (12 substrate examples, up to 95% yields) or oxidative [3 + 2] cycloaddition of phenols and olefins (14 substrate examples, up to 97% yields). Remarkably, a range of natural products, including δ-viniferin, conocarpan, licarin A, homopterocarpin, and pterocarpan, can be facilely and scalably synthesized through a one-step synthesis in high yields (up to 93%), in sharp contrast to multistep routes required by conventional approaches with lower yields (<60%). Comprehensive characterizations reveal that the synthesized 3D COFs with D-A units enable efficient photoinduced carrier separation and migration, thus facilitating the photocatalytic performance. Moreover, the interconnected nanochannels and rigid frameworks in 3D COFs collectively ensure substrate accessibility and structural stability (at least 10 catalytic cycles), much superior to that of the corresponding two-dimensional (2D) COFs. This work provides an innovative approach for facile and efficient photosynthesis of high-value-added chemicals by 3D COFs.