MCM-41 Mesoporous Silica: Efficient and Reusable Catalyst for the Synthesis of 2,4,5-Trisubstituted Imidazoles Under Solvent-Free Conditions

Bismuth (III) Triflate Catalyzed Multicomponent Synthesis of 2,4,5-Trisubstituted Imidazoles

“…Several catalysts have been used for the synthesis of 2,4,5-trisubstituted imidazoles. A few representative examples are cited here and include Yb(OTf) 3 [13], silica sulfuric acid [14], NiCl 2 ⋅6H 2 O [15], microwave irradiation [16], sodium bisulfite [17], tetrabutylammonium bromide [18], MoO 3 /SiO 2 [19], lipase [20], mesoporous silica [21], silica coated magnetite nanoparticles [22], benzethonium chloride [23], lactic acid [24], magnetic nanoparticles [25], CH 3 SO 3 H [26], and mandelic acid [27]. While some of these catalysts are corrosive, a few others require preparation which detracts from their synthetic utility.…”

One-Pot Synthesis of 2,4,5-Triphenyl Imidazoles from 1,2-Diols as Key Reagents

“…The most important of these are (1) one‐pot cyclocondensation of aldehydes with benzoin or benzil and ammonium acetate, (2) one‐pot cyclocondensation of aldehydes with benzil, aromatic amine, and ammonium acetate, and (3) one‐pot cyclocondensation of aromatic nitriles . This has led to the development of new, improved methodologies involving the use of a number of catalysts such as Yb(OPf) 3 , Cu(NO 3 ) 2 /zeolite, potassium dihydrogen phosphate, ZrOCl 2 .8H 2 O, Zr(acac) 4 , NiCl 2 .6H 2 O, p ‐toluenesulfonic acid (PTSA), TiCl 4 ‐SiO 2 , MCM‐41, ZrCl 4 , sodium bisulfite, polymer‐supported zinc chloride, alum, zinc oxide, trichloroisocyanuric acid, tetrabutyl ammonium bromide, ceric ammonium nitrate, nano copper/cobalt ferrites, microwave, amberlyst, novel polymers, antimony trichloride/stannous chloride dihydrate, SbCl 3 /SiO 2 , sulfamic acid/Fe 3 O 4 , and nano aluminum nitride . Although several methodologies have been documented, most of them have their own drawbacks such as poor yields, the use of toxic catalysts, and tedious work‐up.…”

Environmentally benign and highly regioselective ring opening of epoxides accelerated by ultrasound irradiation

“…As a consequence of our interest in the synthesis of organic compounds accelerated by ultrasound (4,32) and to develop an environmentally benign synthesis in chemical research (9,(33)(34)(35), we investigated an efficient and green method in alkylation of nitrogen heterocycles under ultrasound irradiation. The objective of this article is to report the details of alkylation of indoles and imidazoles with epoxides to prepare alcohols using catalytic amount of mesoporous MCM-41 (Scheme 1).…”

“…The mesoporous structure can be controlled by a sophisticated choice of templates such as surfactants and changing reaction parameters such as temperature and compositions. This heterogeneous solid acid catalyst has shown versatile usage and widely applied in the synthesis of various chemicals due to their well-defined micro-structure which forms the basis of uniform active sites and well-controlled steric effects, high acid strength, hydrophilic and hydrophobic properties and reusability that make them promising candidates for catalytic applications (8,9). Therefore, several derivatives of MCM-41 including Mn(bpdo) 2 Cl 2 /MCM-41 (10), Mn-MCM-41 (11,12), Cr-MCM-41 (13) and Al-MCM-41 (14) have been prepared and utilized to catalyze various reactions.…”