Solvent Free Synthesis of α, á-Bis(substituted-benzylidene)cycloalkanones Using Covalently Anchored Sulfonic Acid on Silica Gel (SiO<sub>2</sub>-R-SO<sub>3</sub>H) as an Efficient and Reusable Heterogeneous Catalyst

Abstract

We wish to report a mild and efficient Crossed-Aldol reaction for the synthesis of α, ά-bis(substituted-benzylidene)cycloalkanones in the presence of catalytic amounts of covalently anchored sulfonic acid onto silica gel under heterogeneous and solvent-free conditions. The present methodology offers several advantages such as excellent yields, simple procedure and work up steps, short reaction times and easy recovery of the catalyst. We have also demonstrated that the catalyst can be reused successfully.

Sulfuric Acid Immobilized on Silica Gel as Highly Efficient and Heterogeneous Catalyst for the One-Pot Synthesis of 2,4,5-Triaryl-1H-imidazoles

“…A wide range of important organic reactions can be efficiently catalyzed by these materials, which can be designed to provide different types of acidity as well as high degrees of reaction selectivity. The solid acids generally have high turnover numbers and can be easily separated from the organic components [36,37]. In recent years the H 2 SO 4 immobilized on SiO 2 was used as a catalyst for synthesis of organic compounds [38][39][40][41][42].…”

An Expeditious and Safe Synthesis of Some Exocyclic α,β-Unsaturated Ketones by Microwave-Assisted Condensation of Cyclic Ketones with Aromatic Aldehydes over Anhydrous Potassium Carbonate

“…There has been addition of a good number of other methods in the literature subsequently [7,9,. However, some of the methods available so far suffer from drawbacks like use of toxic or corrosive reagents, expensive catalysts, hazardous solvents, long reaction times, tedious isolation procedure, and so forth, due to which the current literature shows a growing trend for developing environmentally benign methodologies for synthesis of different exocyclic α,β-unsaturated ketones [7,18,23,[33][34][35]37]. Mention of few such recent methods for synthesis of chalcones [38][39][40][41][42][43], a group of structurally related acyclic compounds, may be done in this connection.…”