Synergistic catalysis by Brønsted acid and Pd species on a mesoporous ZSM-5 zeolite for the oxidative homocoupling of terminal alkynes

Abstract

Development of a simple and efficient catalytic system is significant for the synthesis of 1,3-diynes in organic synthesis. Herein, an acidic mesoporous ZSM-5-supported Pd catalyst (Pd@MZSM-5) was able to transform terminal alkynes into 1,3-diynes without any additive under an oxygen atmosphere. The Brønsted acid sites in the Pd@MZSM-5 catalyst could promote the adsorption of alkynes through the interaction of the CC bond with the hydroxyl group, which benefits the active Pd²⁺ species bonding with the CC bond to form the alkynyl-palladium(II) complex. This complex underwent a reductive elimination process to form the 1,3-diyne product.