金属-有机框架衍生的植酸铁催化氢转移高效制备2-芳基苯并噁唑

Metal-Organic Framework Derived Phytate-Iron for Efficient Synthesis of 2-Arylbenzoxazole via Hydrogen Transfer Strategy

金属有机框架及其衍生物在催化领域显示出巨大的应用潜力.利用表面工程方法制备了ZIF-L-Co@phytate-iron(ZIF-L-Co@PA-Fe)异质金属-有机框架(MOF)衍生物.首先,通过植酸(PA)与ZIF-L-Co框架中的有机配体交换,制备植酸功能化的ZIF-L-Co@PA材料.然后,通过Fe^(3+)与配体的配位合成了具有独特异质结构的ZIF-L-Co@PA-Fe.得益于金属-配体相互作用的改进,所设计的ZIF-L-Co@PA-Fe杂化物对氢转移反应表现出优异的催化活性.以ZIF-L-Co@PA-Fe为催化剂,在无溶剂条件下成功地实现了邻硝基苯酚与醇的转移氢环化反应,得到2-取代苯并噁唑衍生物.该催化反应不需要氧化剂、还原剂或碱等额外的添加剂.此外,ZIF-L-Co@PA-Fe配合物具有良好的催化循环稳定性,可重复使用5次而催化活性无明显下降.本工作可为优化其他系列MOF衍生物的催化性能提供有效的指导.

Recently,metal-organic framework(MOF)and its derivatives showed great application potential in catalysis.ZIF-L-Co@phytate-iron(ZIF-L-Co@PA-Fe)heterogeneous MOF derivatives were synthesized by a facile surface engineering method.Phytic acid functionalized ZIF-L-Co(ZIF-L-Co@PA)was firstly prepared through organic ligand exchange of phytic acid(PA).Then,ZIF-L-Co@PA-Fe with unique heterostructure was prepared via coordination occurred between Fe^(3+) and ligands.Benefiting from the greatly modify metal-ligand interactions,the as-designed ZIF-L-Co@PA-Fe hybrids exhibited excellent catalytic activities toward the hydrogen transfer reactions.2-Substituted benzoxazole derivatives were successfully synthesized via transfer hydrogenative annulation of o-nitrophenol with alcohols catalyzed by ZIF-L-Co@PA-Fe under solvent-free conditions.No additional additives,such as oxidants,reductants or bases were required for this reaction.Moreover,ZIF-L-Co@PA-Fe coordination complex showed excellent reusability and could be recycled up to five times without obvious decline in its catalytic activity.This work may provide effective guidance for optimizing the catalytic performance of other series of MOF derivatives.