Oxalic acid was found to be an efficient catalyst for Pechmann condensation, which includes the reaction between phenols and β-keto esters leading to formation of coumarin derivatives. The advantages of present metho...Oxalic acid was found to be an efficient catalyst for Pechmann condensation, which includes the reaction between phenols and β-keto esters leading to formation of coumarin derivatives. The advantages of present methods are the use of cheap and easy available catalyst, solvent-free reaction conditions, better yields and shorter reaction time.展开更多
A simple one-pot synthetic method for the preparation of 2,4,5-triaryl-lH-imidazoles from benzoin or benzil, ammonium acetate, aromatic aldehydes, and ZrOCl2-8H2O catalyst is described. The ZrOCl2-8H2O catalyst was fo...A simple one-pot synthetic method for the preparation of 2,4,5-triaryl-lH-imidazoles from benzoin or benzil, ammonium acetate, aromatic aldehydes, and ZrOCl2-8H2O catalyst is described. The ZrOCl2-8H2O catalyst was found to be equally effective for aromatic and heteroaromatic aldehydes and also for the preparation of substituted 1,4-di(4,5-diphenylimidazol-yl) benzene.展开更多
Differently substituted benzimidazoles have been synthesized in very good yields in solvent-free conditions from o-phenylenediamine and aldehydes in the presence of BF3·OEt2 as a catalyst. The method is applicabl...Differently substituted benzimidazoles have been synthesized in very good yields in solvent-free conditions from o-phenylenediamine and aldehydes in the presence of BF3·OEt2 as a catalyst. The method is applicable to aromatic, unsaturated and aliphatic aldehydes and to substituted o-phenylenediamines without significant differences.展开更多
A simple, efficient, and environment benign route was developed for the preparation of bis-(indolyl)methanes and 14-aryl-14H- dibenzo[aj]xanthenes from condensation of various aromatic aldehydes or ketones with indo...A simple, efficient, and environment benign route was developed for the preparation of bis-(indolyl)methanes and 14-aryl-14H- dibenzo[aj]xanthenes from condensation of various aromatic aldehydes or ketones with indole, and 2-naphthol, respectively, using oxalic acid catalyst in aqueous medium. Use of cheap and easily available catalyst, better yields and simple reaction protocol are the advantages of the present method.展开更多
The tetrahydroquinoline moiety is a structural feature of many natural products. By using a domino reaction of aromatic amines and cyclic enol ethers catalyzed by zirconyl chloride in water, various tetrahydroquinolin...The tetrahydroquinoline moiety is a structural feature of many natural products. By using a domino reaction of aromatic amines and cyclic enol ethers catalyzed by zirconyl chloride in water, various tetrahydroquinoline derivatives were synthesized efficiently. Most cyclized products showed cis selectivity. The cis selectivity was tentatively rationalized due to chelation control in water.展开更多
Oxalic acid has been used as a catalyst for intramolecular cyclisation of 2-hydroxychalcones to form flavones in good yields. The efficiency of the catalyst was proved with a variety of substrates ranging from electro...Oxalic acid has been used as a catalyst for intramolecular cyclisation of 2-hydroxychalcones to form flavones in good yields. The efficiency of the catalyst was proved with a variety of substrates ranging from electron-deficient to electron-rich aryl aldehydes and 2-hydroxychalcone.展开更多
Sulfanilic acid has been found to be an efficient catalyst for the synthesis of 1,5-benzodiazepines from o-phenylenediamine and ketones. This method is simple, effective and environmentally friendly and gives better y...Sulfanilic acid has been found to be an efficient catalyst for the synthesis of 1,5-benzodiazepines from o-phenylenediamine and ketones. This method is simple, effective and environmentally friendly and gives better yields.展开更多
ZrOCl2·8H2O catalyzed environmentally benign synthesis of isobenzofuran-1(3H)-ones are described.ZrOCl2·8H2O appeared to be an excellent catalyst for the condensation and reactions.Reaction of phthalaldehy...ZrOCl2·8H2O catalyzed environmentally benign synthesis of isobenzofuran-1(3H)-ones are described.ZrOCl2·8H2O appeared to be an excellent catalyst for the condensation and reactions.Reaction of phthalaldehydic acid(2-carboxybenzaldehyde) with methylaryl and cyclic ketones was initiated by condensation and occurred in one step providing excellent yields(90-98%).展开更多
文摘Oxalic acid was found to be an efficient catalyst for Pechmann condensation, which includes the reaction between phenols and β-keto esters leading to formation of coumarin derivatives. The advantages of present methods are the use of cheap and easy available catalyst, solvent-free reaction conditions, better yields and shorter reaction time.
文摘A simple one-pot synthetic method for the preparation of 2,4,5-triaryl-lH-imidazoles from benzoin or benzil, ammonium acetate, aromatic aldehydes, and ZrOCl2-8H2O catalyst is described. The ZrOCl2-8H2O catalyst was found to be equally effective for aromatic and heteroaromatic aldehydes and also for the preparation of substituted 1,4-di(4,5-diphenylimidazol-yl) benzene.
文摘Differently substituted benzimidazoles have been synthesized in very good yields in solvent-free conditions from o-phenylenediamine and aldehydes in the presence of BF3·OEt2 as a catalyst. The method is applicable to aromatic, unsaturated and aliphatic aldehydes and to substituted o-phenylenediamines without significant differences.
文摘A simple, efficient, and environment benign route was developed for the preparation of bis-(indolyl)methanes and 14-aryl-14H- dibenzo[aj]xanthenes from condensation of various aromatic aldehydes or ketones with indole, and 2-naphthol, respectively, using oxalic acid catalyst in aqueous medium. Use of cheap and easily available catalyst, better yields and simple reaction protocol are the advantages of the present method.
文摘The tetrahydroquinoline moiety is a structural feature of many natural products. By using a domino reaction of aromatic amines and cyclic enol ethers catalyzed by zirconyl chloride in water, various tetrahydroquinoline derivatives were synthesized efficiently. Most cyclized products showed cis selectivity. The cis selectivity was tentatively rationalized due to chelation control in water.
文摘Oxalic acid has been used as a catalyst for intramolecular cyclisation of 2-hydroxychalcones to form flavones in good yields. The efficiency of the catalyst was proved with a variety of substrates ranging from electron-deficient to electron-rich aryl aldehydes and 2-hydroxychalcone.
文摘Sulfanilic acid has been found to be an efficient catalyst for the synthesis of 1,5-benzodiazepines from o-phenylenediamine and ketones. This method is simple, effective and environmentally friendly and gives better yields.
文摘ZrOCl2·8H2O catalyzed environmentally benign synthesis of isobenzofuran-1(3H)-ones are described.ZrOCl2·8H2O appeared to be an excellent catalyst for the condensation and reactions.Reaction of phthalaldehydic acid(2-carboxybenzaldehyde) with methylaryl and cyclic ketones was initiated by condensation and occurred in one step providing excellent yields(90-98%).