K2CO3-Mediated Regioselective Synthesis of Isoxazoles and Pyrazolines

Abstract

3,5-Diarylisoxazoles and 1,3,5-triarylpyrazolines are synthesized via Michael addition of "hydroxylamine hydrochloride, phenylhydrazine" respectively over chalcones followed by cyclization using K 2 CO 3 as solid support. Reactions are shown to be highly regioselective regardless of the nature of the substituent in the substrates and afforded single isoxazole and pyrazoline isomer in excellent yields.

Eco-friendly synthesis and antimicrobial activities of some 1-phenyl-3(5-bromothiophen-2-yl)-5-(substituted phenyl)-2-pyrazolines

“…Fly ash is a waste air pollutant, and it has many chemical species [10,33], such as SiO 2 , Fe 2 O 3 , Al 2 O 3 , CaO, and MgO, and insoluble residues. The waste fly ash is converted into useful catalyst fly ash: H 2 SO 4 by mixing fly ash and sulphuric acid.…”

“…In 1998, Powers et al [9] have reported the reaction of chalcones with phenyl hydrazine hydrochloride in the presence of sodium hydroxide and absolute ethanol at 70°C, where the longer reaction time is the disadvantage of the reaction. K 2 CO 3 -mediated microwave irradiation has been shown to be an efficient method for the synthesis of pyrazolines [10]. The regioselective formation of pyrazolines has been synthesized by the reaction of substituted hydrazine with α,β-unsaturated ketones [11,12].…”

Synthesis and antimalarial evaluation of 1, 3, 5-trisubstituted pyrazolines

“…A variety of methods have been reported for the synthesis of 1,3,5-trisubstituted pyrazolines [27][28][29][30][31]. Among the simplest methods, condensation of an a,b-unsaturated ketone with an acid hydrazide in glacial acetic acid (bp 117 C) under reflux was reported by Fischer and Knö venagel [27].…”

Synthesis, characterization and antimicrobial evaluation of 1-((5,3-diaryl)-4,5-dihydro-1H-pyrazol-1-yl)propan-1-one

“…Of particular interest is the use of 1H-pyrazoles as synthetic intermediates for preparing cyclopropane [17][18][19] and pyrazole derivatives [1,[20][21][22][23][24][25][26]. 1H-Pyrazoles have usually been prepared by starting from aldehydes or ketones, which have either actual or potential α,β-unsaturation [1,[27][28][29][30][31][32][33][34][35][36][37][38][39][40][41]. 1,3-Dipolar cycloadditions between diazoalcanes and different types of molecules containing activated double bonds are also exploitable reactions [1,16,17,42,43].…”