Tandem Knoevenagel–Michael Reaction of 1-Phenyl-3-methyl-5-pyrazolone with Aldehydes Using 3-Aminopropylated Silica Gel as an Efficient and Reusable Heterogeneous Catalyst

An efficient synthesis of tetrahydropyrazolopyridine derivatives by a one-pot tandem multi-component reaction in a green media

“…Intermediate 7 has already been reported to be the final product of the reaction of 1-phenyl-3-methyl-5-pyrazolone with an aldehyde. 31,32 Finally, nucleophilic attack of ammonia on intermediate 7 followed by intramolecular cyclization leads to compound 8 which can then tautomerize to form the final product 5. …”

A multi-component reaction for the direct access to 4,4'-(phenylmethylene)bis(1H-pyrazol-5-ol)-3-carboxylates using nano-NiZr4(PO4)6 in water

“…The synthesis of 1-phenyl-1Hpyrazol-5-ols has been reported using MCR in the presence of Ce(SO 4 ) 2 .4H 2 O [13], silica-bonded S-sulfonic acid [14], 1,3,5-tris(hydrogensulfato) benzene [15], 1sulfopyridinium chloride [16], acetic acid [17], and nano-CeO 2 [18]. Some of these methods have certain disadvantages, including long reaction times, use of toxic and non-reusable catalyst, and operation under speci c conditions [19,20]. The possibility of accomplishing multicomponent reactions in aqueous media with a heterogeneous catalyst could expand their eciency from cost-e ectiveness and environmental points of view [21,22].…”

An efficient and green one-pot three-component synthesis of 4,4′-(arylmethylene)bis(1H-pyrazol-5-ol)s catalyzed by 2-hydroxy ethylammonium propionate

“…The condensation of aldehydes with two equivalents of 3-methyl-1-phenyl-5-pyrazolone is a known used route for synthesizing 4,4′-(arylmethylene)bis(1H-pyrazol-5-ol)s. Xanthan sulfuric acid (4), phosphomolybdic acid (5), silica sulfuric acid (6), 3-aminopropylated silica gel (7), sodium dodecyl sulfate (8), tetramethyl-tetra-3,4-pyridinoporphyrazinato copper(II) methyl sulfate (9), poly(ethylene glycol)-bound sulfonic acid (10), cellulose sulfuric acid (11), lithium hydroxide monohydrate (12), 1,3,5-tris(hydrogensulfato) benzene (13), sulfuric acid ([3-(3-silicapropyl)sulfanyl]propyl)ester (14), ethylenediammonium diacetate (15), 2-hydroxy ethylammonium acetate (16), N-(3-silicapropyl)-N-methyl imidazolium hydrogen sulfate (17), benzyltriethylammonium chloride (18), ceric ammonium nitrate (19), silica-bonded S-sulfonic acid (20), 1,3-disulfonic acid imidazolium tetrachloroaluminate (21), and 1-sulfopyridinium chloride (22) can be used as catalysts for this transformation. Hasaninejad et al reported the synthesis of 4,4′-(arylmethylene)bis(1H-pyrazol-5-ol)s by the condensation of aldehydes with two equivalents of 3-methyl-1-phenyl-5-pyrazolone in the absence of catalyst (23)(24)(25).…”