Cellulose beads: A new versatile solid support for microwave-assisted synthesis. Preparation of pyrazole and isoxazole libraries

Journal of Combinatorial Chemistry

Volumn 5, Issue 4, 2003, Pages 465-471

  De Luca, Lidia ^a   Giacomelli, Giampaolo ^a   Porcheddu, Andrea ^a   Salaris, Margherita ^a   Taddei, Maurizio ^b  

^a UNIVERSITY OF SASSARI   (Italy)

^b UNIVERSITY OF SIENA   (Italy)

Author keywords

[No Author keywords available]

Indexed keywords

ANILINE DERIVATIVE; CELLULOSE; ENAMINE; HYDRAZINE DERIVATIVE; HYDROXYLAMINE; ISOXAZOLE DERIVATIVE; POLYMER; PYRAZOLE DERIVATIVE;

ARTICLE; CHEMICAL REACTION; COST BENEFIT ANALYSIS; HEATING; MICROWAVE RADIATION; SYNTHESIS;

CELLULOSE; CHROMATOGRAPHY, HIGH PRESSURE LIQUID; COMBINATORIAL CHEMISTRY TECHNIQUES; HYDRAZINES; HYDROXYLAMINES; ISOXAZOLES; MAGNETIC RESONANCE SPECTROSCOPY; MICROSPHERES; MICROWAVES; PYRAZOLES; SPECTROMETRY, MASS, ELECTROSPRAY IONIZATION;

EID: 0141563686     PISSN: 15204766     EISSN: None     Source Type: Journal    
DOI: 10.1021/cc0201187     Document Type: Article

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110. In a closed-vessel system, the process is significantly less effective.
111. 2O) is removed rapidly from the reaction mixture and, therefore, from the equilibrium.
112. iPrOH/THF (2/1) for increasing the swelling of PS resin. Pyrazoles 5a-c and isoxazoles 6a-c prepared with PS support were recovered after aqueous workup in ∼70-75% yield (purity >94% as judged by HPLC analysis). The reaction times were comparable both under conventional heating and under microwave irradiation. At last, using recycled PS support, the purity of final compound decreased to 80% (65% for PS subjected at conventional heating), so that in the second cycle, it was necessary to purify the heterocycle by chromatography or preparative HPLC. Moreover, no increase in purity was observed using a microwave irradiation.
113. 2 rather than with a basic aqueous solution of β-naphthol. The cellulose bead immediately changed color from white to red in the presence of free aniline amine.
114. Iron(III) was able to form an intensely colored complex (rust-brown) with enolizable ketones. Therefore, this old colorimetric assay is suitable and sensitive to detect the presence (absence) of β-dicarbonyl compounds on solid support.
115. See experimental part in ref 25.