L-aspartic acid chelan-Cu (II) complex coted on ZrFe2O4 MNPs catalyzed one-pot annulation and cooperative geminal-vinylogous anomeric-based oxidation reactions

In the present study, a novel chelan complex - L-aspartic acid with copper (II) - is well prepared on the surface of silica-modified nanomagnetic zirconium ferrite as a new catalytic support for high-performance catalysis ap-plications. Regarding the CPTMS utilization as a linker, both of the carboxylate functional groups in L-aspartic acid remained unchanged and, finally, coordinated to metal sites. Moreover, the [ZrFe2O4@-SiO2-n-Pr-ASP-Cu(II)] complex exhibited significant catalytic activity in the synthesis of Pyrano[2,3-c]pyrazoles and 2-amino-3-cyanopyridine derivatives under green conditions. The mechanistic studies revealed the same Knoevenagel condensation - Michael addition - cyclization sequence for both of these reactions. However, regarding 2-amino-3-cyanopyridines, a cooperative geminal-vinylogous anomeric-based oxidation occurred at the last step, leading to the aromatization of 1,4-dihydropyridine intermediates to pyridine. Notably, a wide variety of aryl and hetero-aryl aldehydes - bearing both electron-releasing and electron-withdrawing groups - were employed for the synthesis of six-membered heterocycles.

Automated summary

In this study, a novel chelan complex - L-aspartic acid with copper (II) - is developed on the surface of silica-modified nanomagnetic zirconium ferrite as a new catalytic support. The resulting complex exhibits significant catalytic activity in the synthesis of Pyrano[2,3-c]pyrazoles and 2-amino-3-cyanopyridine derivatives. Mechanistic studies revealed a similar reaction sequence for both reactions, with an additional oxidation step for the synthesis of 2-amino-3-cyanopyridines to pyridines. Various aryl and hetero-aryl aldehydes were employed for the synthesis of six-membered heterocycles.