Cellulose beads: a new versatile solid support for microwave- assisted synthesis. Preparation of pyrazole and isoxazole libraries.
The synthesis of libraries of substituted pyrazoles and isoxazoles has been developed via in situ generation of polymer-bound enaminones. The synthetic protocol makes use of commercially available aniline cellulose, a low-cost and versatile biopolymer, under very mild conditions. This new support allowed us to carry out reactions in polar solvents under both conventional heating and MW irradiation without degradation of the polymer. The reaction between cellulose-bound enaminone and hydroxylamine or hydrazines to afford the target heterocycles in high yields directly in solution is the key step. The support can be conveniently recycled.
De Luca
Lidia
L
Dipartimento di Chimica, Università degli Studi di Sassari, via Vienna 2, I-07100 Sassari, Italy.
Giacomelli
Giampaolo
G
Porcheddu
Andrea
A
Salaris
Margherita
M
Taddei
Maurizio
M
D002482:Cellulose / Q000737:chemistry*; D002851:Chromatography, High Pressure Liquid; D020650:Combinatorial Chemistry Techniques / Q000379:methods*; D006834:Hydrazines / Q000737:chemistry; D006898:Hydroxylamines / Q000737:chemistry; D007555:Isoxazoles / Q000138:chemical synthesis* / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D008863:Microspheres; D008872:Microwaves; D011720:Pyrazoles / Q000138:chemical synthesis* / Q000737:chemistry; D021241:Spectrometry, Mass, Electrospray Ionization
D006834:Hydrazines; D006898:Hydroxylamines; D007555:Isoxazoles; D011720:Pyrazoles; D002482:Cellulose