Different aromatic aldehydes and cinnamaldehyde undergo cross-aldol condensation with chroman-4-ones and1-thiochroman-4-ones in the presence of amberlyst-15 under microwave irradiation in solvent free condition to afford rapidly the correspondingE-3-arylidene andE-3-cinnamylidene derivatives, respectively, in high yield. This process is simple, efficient and environmentally benign.
Microwave irradiation of ketosemicarbazones on wet silica supported sodium bismuthate under environmentally benign solvent-free condition provides a fast, efficient and simple method for regeneration of ketones in good yields.
One-pot and efficient protocol for preparation of some potent pharmaceutically valuable coumarin derivatives under solvent-free condition via direct coupling using biologically nontoxic organocatalyst, calix[4]arene tetrasulfonic acid (CSA), was introduced. Calix[4]arene sulfonic acid has been incorporated lately as a magnificent and recyclable organocatalyst for the synthesis of some organic compounds. Nontoxicity, solvent-free conditions, good-to-excellent yields for pharmaceutically significant structures, and especially ease of catalyst recovery make this procedure valuable and environmentally benign.
Lanthanum chloride was found to be an effective catalyst for the facile and one-pot synthesis of polysubstituted imidazoles under solvent free condition in excellent yields. This method elucidates urea/thiourea, as an environmentally benign source of ammonia for the synthesis of polysubstituted imidazoles. The work-up procedure is very simple and the products don’t require further purification.
Facile Condensation of Aromatic Aldehydes with Chroman-4-ones and 1-Thiochroman-4-ones Catalysed by Amberlyst-15 under Microwave Irradiation Condition