A convenient synthesis of 3- and 5-amino-1H-pyrazoles via 3(5)-amino-4-(ethylsulfinyl)-1H-pyrazole desulfinylation
摘要:
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.
Reaction of beta-bromo alpha-alkylthiocinnamonitriles with various substituted methyl salicylates followed by treatment with AlCl3/PhNO2 provides 3-cyanoflavones. (C) 2003 Elsevier Ltd. All rights reserved.