The bulky Pd-PEPPSI-embedded conjugated microporous polymer-catalyzed Suzuki–Miyaura cross-coupling of aryl chlorides and arylboronic acids†
Through a post-synthesis method, a type of bulky N-heterocyclic carbene (NHC) functionalized conjugated microporous polymer supporting a palladium-based molecular catalyst has been developed. The resulting heterogeneous catalyst Pd-PEPPSI-CMP, showing greater steric hindrance around the palladium center than a monomer Pd-PEPPSI-IPr catalyst, demonstrated much higher catalytic efficiency for Suzuki–Miyaura cross-coupling reactions of aryl chlorides under aerobic conditions. The superior utility of Pd-PEPPSI-CMP in catalysis was elucidated through the broad substrate scope (30 examples, 76–98% yields), the tolerance for a variety of functional groups, the excellent recyclability (15 cycles), and an example of gram-scale synthesis (10 mmol). Moreover, its utility has been highlighted via the synthesis of a bioactive molecule (boscalid) and the direct late-stage functionalization of pharmaceuticals (4 examples, 76–85% yields). These results demonstrated that Pd-PEPPSI-CMP could be used as an efficient and robust heterogeneous catalyst with potential industrial applications.