Highly chemoselective acetalization of carbonyl compounds catalyzed by a novel recyclable ammonium triflate-functionalized silica

A novel ammonium triflate-functionalized silica (NH4+OTf−@SiO2, ATFS) has been prepared and characterized by simple operation from commercially available and relatively cheap starting materials. Various types of aldehydes as well as cyclic ketones were selectively converted to the corresponding 1,3-dioxanes in the presence of ethyl orthoformate, 1,3-propanediol and a catalytic amount of ATFS catalyst via an in situ acetal-exchange process. The catalyst can be recovered and reused for at least six reaction cycles without considerable loss of its reactivity.

Graphical abstractVarious types of aldehydes as well as cyclic ketones were selectively converted to the corresponding 1,3-dioxanes in the presence of ethyl orthoformate, 1,3-propanediol and a catalytic amount of a novel ammonium triflate-functionalized silica (NH4+OTf −@SiO2, ATFS) via an in situ acetal-exchange process. The catalyst can be recovered and reused for at least six reaction cycles without considerable loss of its reactivity.Figure optionsDownload full-size imageDownload as PowerPoint slide