A Hydrazone‐Based Covalent Organic Framework as an Efficient and Reusable Photocatalyst for the Cross‐Dehydrogenative Coupling Reaction of <i>N</i> ‐Aryltetrahydroisoquinolines

A hydrazone‐based covalent organic framework (COF) was synthesized by condensation of 2,5‐dimethoxyterephthalohydrazide with 1,3,5‐triformylbenzene under solvothermal conditions. The COF material exhibits excellent porosity with a BET surface area of up to 1501 m 2 g −1 , high crystallinity, and good thermal and chemical stability. Moreover, it showed efficient photocatalytic activity towards cross‐dehydrogenative coupling (CDC) reactions between tetrahydroisoquinolines and nucleophiles such as nitromethane, acetone, and phenylethyl ketone. The metal‐free catalytic system also offers attractive advantages including simplicity of operation, wide substrate adaptability, ambient reaction conditions, and robust recycling capability of the catalyst, thus providing a promising platform for highly efficient and reusable photocatalysts.