A convenient synthesis of 3- and 5-amino-1H-pyrazoles via 3(5)-amino-4-(ethylsulfinyl)-1H-pyrazole desulfinylation
作者:Frédéric Lassagne、Katia Snégaroff、Thierry Roisnel、Ekhlass Nassar、Florence Mongin
DOI:10.1515/hc.2011.026
日期:2011.1.1
Syntheses of 5-amino-3-aryl- and 3-amino-5-aryl-1H-pyrazoles from beta-bromo-alpha-(ethylsulfanyl)cinnamonitrile are described. The beta-bromo-alpha-(ethylsulfanyl) cinnamonitriles were oxidized with H(2)O(2) to the corresponding beta-bromo-alpha-(ethylsulfinyl) cinnamonitriles. Subsequent treatment of the resulting sulfoxides with hydrazine hydrate or methylhydrazine followed by hydrochloric acid hydrolysis afforded 5-amino-3-aryl- and 3-amino-5-aryl-1H-pyrazoles, respectively, in good yields.