Synthesis of ۲-substituted benzoxazoles by hydrophobic ethyl-bridged periodic mesoporous organosilica functionalized sulfonic acid

A series of metal-free tandem reactions for the synthesis of pharmaceutical and industrial ۲-substituted benzoxazoles from isothiocyanates with ۲-aminophenol in the presence of Et-PMO-Me-PrSO۳H (۱b) as a solid acid were carried out efficiently and selectively in solvent free condition. A significant selectivity toward ۲-mercaptobenzoxazole derivatives due to hydrophobic nature of the solid catalyst was observed. Simple experimental procedure with novel selective approach toward benzoxazoles accompanied by green and reusable catalyst could be considered as an alternative feature of this protocol to the existing methods for the synthesis of ۲-substituted benzoxazoles derivatives.