Spiroisoxazole and spiropyrazole derivatives were obtained in a four-component reaction of active isoxazol- or pyrazol-5-ones with aromatic aldehydes, phenacyl chloride and AcOH-AcONH4 mixture. The reaction sequence is highly chemo- and diastereoselective affording good yields of spiroisoxazoles in refluxing ethanol, while efficient formation of spiropyrazoles is closely related to the use of a microwave-assisted protocol.
An improved diastereoselective synthesis of spiroazoles using multicomponent domino transformations
ALTIERI, ELISA;CORDARO, Massimiliano;GRASSI, Giovanni;RISITANO, Francesco;SCALA, ANGELA
2010-01-01
Abstract
Spiroisoxazole and spiropyrazole derivatives were obtained in a four-component reaction of active isoxazol- or pyrazol-5-ones with aromatic aldehydes, phenacyl chloride and AcOH-AcONH4 mixture. The reaction sequence is highly chemo- and diastereoselective affording good yields of spiroisoxazoles in refluxing ethanol, while efficient formation of spiropyrazoles is closely related to the use of a microwave-assisted protocol.File in questo prodotto:
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