Construction of heterogeneous FLPs based on COFs supported Lewis acid and its application in terminal alkyne hydrogenation

Frustrated Lewis Pairs (FLPs) were widely used as metal-free catalysts in current chemistry. More and more researches began to focus on heterogeneous FLPs to meet industrial production needs. Nevertheless, these reported heterogeneous FLPs were mostly constructed based on solid-state Lewis bases (LB) combined with small molecule Lewis acids (LA), such as B(C 6 F 5 ) 3 , which led to incomplete recovery of more expensive LA. In order to construct heterogeneous FLPs with stability and cyclicity based on solid LA, herein, we propose the strategy of first preparing heterogeneous COFs-B(C 6 F 5 ) 2 (solid LA) by reducing part of the C=N bonds on COFs through H-B(C 6 F 5 ) 2 , followed by introducing 1,8-diazabicycloundecano-7-ene (DBU) to construct semi-solid heterogeneous FLPs COFs-B(C 6 F 5 ) 2 /DBU. Simultaneously, these FLPs catalysts showed excellent catalytic performance in the field of terminal alkyne hydrogenation to olefins and could be cycled 8 times without loss of catalytic activity.