Physically mixed catalytic system of amino and sulfo-functional porous organic polymers as efficiently synergistic co-catalysts for one-pot cascade reactions

Sun, ZM (Sun, Zunming)^{[ 1 ]} ; Liu, FY (Liu, Fuyao)^{[ 1 ]} ; Yang, XY (Yang, Xinyue)^{[ 1 ]} ; Huang, XP (Huang, Xianpei)^{[ 1 ]} ; Zhang, MM (Zhang, Mengmeng)^{[ 1 ]} ; Bian, GM (Bian, Guomin)^{[ 2 ]} ; Qi, YL (Qi, Yonglin)^{[ 2 ]} ; Yang, XL (Yang, Xinlin)^{[ 1 ]} ; Zhang, WQ (Zhang, Wangqing)^{[ 1 ]}

NEW JOURNAL OF CHEMISTRY, 2020, 44(22): 9546-9556

DOI: 10.1039/d0nj01357a

摘要

In this article, acid/base bi-functional polymeric materials were prepared using physically mixed porous poly(divinylbenzene-co-4-vinylbenzenesulfonic acid) (P(DVB-VBS)) with sulfonic acid groups and poly(divinylbenzene-co-4-vinylbenzyl amine) (P(DVB-VBA)) with amino groups, which were synthesized by solvothermal polymerization of crosslinker DVB with either phenyl 4-vinylbenzenesulfonate (PVBS) or 4-vinylbenzyl amine hydrochloride (VBAH) functional monomers together with subsequent hydrolyzation or alkaline treatment. The bi-functional polymeric materials were utilized as a synergistic catalytic system for one-pot cascade reactions including deacetalization-Henry condensation reaction, deacetalization-Knoevenagel condensation reaction and the transformation of 3,4-dihydropyran derivatives to alpha-ester cyclohexenone compounds. The crosslinked polymeric frameworks effectively isolated sulfonic acid and primary amine groups to ensure their roles as both acid and base catalyst simultaneously in a one-pot system. The hierarchical porosity of a physically mixed acid/base co-catalyst system provided the possibility for the multi-step transformation of more complex substrates.