Iron(III) tosylate catalyzed synthesis of 3,4-dihydropyrimidin-2(1H)-ones/thiones via the Biginelli reaction

12‐Tungstosilicic Acid H4[W12SiO40] Over Natural Bentonite as a Heterogeneous Catalyst for the Synthesis of 3,4‐dihydropyrimidin‐2(1H)‐Ones

“…This method furnished products in poor yield in the case of aliphatic and substituted aromatics aldehydes . Due to their important medicinal activities, several improved protocols have been reported in the presence of Bronsted and Lewis acids . Despite their excellent catalytic activity, severe problems associated with them including harsh reaction condition, difficulty in separation, high cost, recycling and recovery of catalyst are a major concern and especially some environmental considerations.…”

Metal‐Catalyzed Routes to Dibenzodiazepines (DBDAs) and Structural Analogues: Recent Advances

“…[46][47][48][49] Recently, Tarannum and Siddiqui [50] reported a novel catalytic system, that consisted of Fe(OTs) 3 / SiO 2 , which was used for the multicomponent synthesis of the dibenzodiazepine analogues 29 (which contained only one benzene unit) under solvent-free conditions (Scheme 16). Its lack of sensitivity to moisture, ease in handling and low toxicity makes it an attractive catalyst for organic synthesis.…”

1,3-Disulfonic acid benzimidazolium chloride as an efficient and recyclable ionic liquid catalyst for the synthesis of 3,4-dihydropyrimidine-2-(1H)-ones/thiones

“…DHPMs have received special attention given their wide range of biological and pharmaceutical activities, including antibacterial, antiviral, anticancer, antitumor, antifungal, antioxidant, anti-inflammatory, and antihypertensive properties, their use as calcium channel modulators, a 1A -antagonists, neuropeptide Y(NPY) antagonists, and other related properties [12][13][14][15][16]. Over the past decade, several methods have been reported for the synthesis of DHPMs using LaCl 3 -graphite [15], CuCl 2 Á2H 2 O [16], Yb(OTf) 3 [17], phytic acid [18], triphenylphosphine (PPh 3 ) [19], silica-bonded N-propyl sulfamic acid [20], Fe(OTs) 3 Á6H 2 O [21], bioglycerol-based sulfonic acid functionalized carbon [22], sulfonated carbon materials (SCM) [ [33] and silica-bonded S-sulfonic acid (SBSSA) [34]. While existing synthetic methods are effective for the preparation of target compounds, some suffer shortcomings such as long reaction time (2.5-43 h), elevated temperature (refluxing EtOH or MeCN and solvent-free 140°C), low yields, the use of hazardous organic solvents (e.g., EtOH, MeCN, AcOH, THF, isopropanol) or unrecyclable catalysts (e.g., CuCl 2 Á2H 2 O, InCl 3 , Yb(OTf) 3 , Fe(OTs) 3 Á6H 2 O), and poor compliance with the green chemistry protocols.…”