Efficient Catalytic Performance for Acylation-Nazarov Cyclization Based on an Unusual Postsynthetic Oxidization Strategy in a Fe(II)-MOF.

A rare example of SC-SC triggered by Cu heterogeneous oxidation was demonstrated in a Fe(II)-based MOF {[Fe(L)(HO)]·3HO} (1), which occurred a slow conversion into an oxidized MOF 2 ({[Fe(L)(HO)]·3(OH)} ) with retention of single crystallinity. The Fe → Fe progress of the reaction oxidation was proved by single crystal XRD, PXRD, XPS, Fe Mössbauer spectroscopy, and UV-vis. We used 1 and 2 as catalysts to catalyze the tandem Nazarov cyclization, and the results show that acylation products were only harvested when 1 was a catalyst, while the oxidized transformer 2 lead mainly to the formation of cyclization products under identical conditions. Through the test of different substrates, 2 can be a good heterogeneous catalyst candidate for the formation of cyclopentenone[ b] benzenes. This work provides a new way to design efficient and hard-synthesized heterogeneous catalyst materials.