Brønsted–Lewis dual acidic ionic liquid immobilized on mesoporous silica materials as an efficient cooperative catalyst for Mannich reactions

Abstract

Novel mesoporous silica supported ILs have been prepared and successfully applied as a heterogeneous catalyst in Mannich reactions.

Hf(OTf)4 as a Highly Potent Catalyst for the Synthesis of Mannich Bases under Solvent-Free Conditions

“…Flash column chromatography (hexane/ethyl acetate 10:1) afforded the desired Mannich base in pure form. The characterization data of Mannich bases 1-10, 12-14, 17-19, 24, 26, and 30-32 were in good agreement with those reported in literatures [17,19,20,22,25,36,[47][48][49][50].…”

“…Therefore, highly potent, low-cost, and non-toxic metal Lewis acid catalysts for Mannich reaction are still highly desired. Recently, novel heterogeneous catalysts such as nanoparticle-supported/encapsulated solid acids [35][36][37], mesoporous materials [38,39], metal nanoparticles [40], and metal-coordinated polymers [41,42] have provided improved catalyst recyclability. However, the preparation of these specific catalysts greatly limits their practical applications.…”

Brønsted acidic ionic liquid-promoted direct C3-acylation of N-unsubstituted indoles with acid anhydrides under microwave irradiation

“…40,41 Recently, Brønsted acidic ionic liquids (ionic liquids with acidic properties) have been widely used for various organic transformations due to their unique properties. 19,[42][43][44][45][46][47][48][49][50][51][52][53][54][55][56] Nevertheless, to the best of our knowledge, they have never been used for the direct C3-acylation of N-unsubstituted indoles. Thus, we now report the development of a highyielding and regioselectivity method for the C3-acylation N-unsubstituted indoles using Brønsted acidic ionic liquid as an efficiently homogeneous catalyst under microwave irradiation.…”

Tunable Aryl Imidazolium Recyclable Ionic Liquid with Dual Brønsted–Lewis Acid as Green Catalyst for Friedel–Crafts Acylation and Thioesterification

“…Previous investigations have reported that ionic liquids exhibit the dual Brønsted and Lewis acidic property, the halogen-free Brønsted-Lewis acidic ionic liquids were synthesized and exploited to catalyze the esterification of caprylic acid with methanol. The novel multifunctional MCM-41 as Brønsted-Lewis acidic ionic liquids were prepared and tested for their catalytic activities in one-pot three-component Mannich reactions [25][26][27]. Benzoylation of anisole catalyzed by metal triflate and chloroindate (III) by Lewis-acid ionic liquid were used in Friedel-Crafts reaction [28,29].…”