A practical synthesis of 2-aminobenzothiazoles via the tandem reactions of 2-haloanilines with isothiocyanates catalyzed by immobilization of copper in MCM-41

The heterogeneous tandem reactions of 2-haloanilines with isothiocyanates were achieved in DMSO using Et3N as base at 80 °C in the presence of a 3-(2-aminoethylamino)propyl-functionalized MCM-41-immobilized copper(II) complex [MCM-41-2N-CuSO4], yielding a variety of 2-aminobenzothiazoles in good to excellent yields. This heterogeneous copper catalyst exhibited higher activity than CuSO4 and can be recovered and recycled by a simple filtration of the reaction solution and used for at least 10 consecutive trials without any decreases in activity.

Graphical abstractThe heterogeneous tandem reactions of 2-haloanilines with isothiocyanates were achieved in DMSO using Et3N as base at 80 °C in the presence of MCM-41-2N-CuSO4, yielding a variety of 2-aminobenzothiazoles in good to excellent yields.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► The heterogeneous Cu-catalyzed reaction of 2-haloanilines with isothiocyanates was described. ► The MCM-41-2N-CuSO4 showed higher catalytic activity than CuSO4. ► This copper catalyst can be reused at least 10 times without any decrease in activity. ► Our catalytic system provides a practical procedure for the synthesis of 2-aminobenzothiazoles.