Silica Gel-Immobilized 1,2-Benzenedisulfonimide: A New and Versatile Brønsted Acid Heterogeneous Catalyst

Abstract

a derivative of 1,2-benzenedisulfonimide, a strong and versatile Brønsted acid catalyst, has been immobilized on 3-aminopropil silica gel, by means of an amide bond, to afford a new heterogeneous catalyst. Its structure has been confirmed using IR and NMR spectroscopy. This new catalyst has been employed in five different organic reactions giving excellent results. At the end of the processes, it was recovered by easy filtration and reused without loss in its catalytic activity.

Silica gel-immobilised chiral 1,2-benzenedisulfonimide: a Brønsted acid heterogeneous catalyst for enantioselective multicomponent Passerini reaction

“…This objective was easily achieved by oxidising the methyl groups of (−) 3 with KMnO 4 in a basic environment ( Scheme 2 ), obtaining in this way (−)-4,5-dicarboxy-3,6-bis(1-naphthyl)-1,2-benzenedisulfonimide (10). As reported in our previous paper, 13 the condensation between NH 2 and COOH groups was promoted by N -(3-dimethylaminopropyl)- N -ethylcarbodiimide hydrochloride (EDC; Scheme 2 ). The material obtained was isolated via filtration over Büchner funnel and was washed firstly with dilute hydrochloric acid in order to fully restore the acid function of the sulfonimide and then with acetone in order to remove any possible organic residue.…”

“…In continuation of our research, we anchored, through an amide bond, an appropriately functionalised derivative of 1, namely 1,2-benzenedisulfonimide-4-yl propionic acid (8), to a 3-aminopropyl functionalized silica gel support (7) thus obtaining a new specie having increased robustness and recyclability with respect to (1), furthermore paving the way for its successful employment in heterogeneous catalysis (9; Scheme 1 ). 13 …”