Photocatalytic Oxidative [3+2] Cycloaddition for Pyrrolo[2,1‐a]isoquinoline Synthesis Using a Porphyrin‐Based Covalent Organic Framework.

By using a catalytic amount of a porphyrin‐based covalent organic framework (Por‐Ad‐COF) as the efficient recyclable photocatalyst, the photocatalytic oxidative [3+2] cycloaddition reaction between tetrahydroisoquinolines and N‐substituted maleimides was developed under aerobic conditions at room temperature. Various substituted pyrrolo[2,1‐a]isoquinolines were obtained in moderate to good yields via the dipolar [3+2] cycloaddition and oxidative aromatization cascade process under visible light irradiation. This was the first example to employ the covalent organic framework as the heterogeneous photocatalyst to perform the photocatalytic dipolar [3+2] cycloaddition reaction for the synthesis of pyrrolo[2,1‐a]isoquinolines. [ABSTRACT FROM AUTHOR]