The synthesis of highly substituted isoxazoles by electrophilic cyclization: an efficient synthesis of valdecoxib.
A large number of functionally substituted 2-alkyn-1-one O-methyl oximes have been cyclized under mild reaction conditions in the presence of ICl to give the corresponding 4-iodoisoxazoles in moderate to excellent yields. The resulting 4-iodoisoxazoles undergo various palladium-catalyzed reactions to yield 3,4,5-trisubstituted isoxazoles, including valdecoxib.
Waldo
Jesse P
JP
Department of Chemistry, Iowa State University, Ames, Iowa 50011, USA.
Larock
Richard C
RC
D002384:Catalysis; D003500:Cyclization; D007555:Isoxazoles / Q000138:chemical synthesis* / Q000737:chemistry; D015394:Molecular Structure; D010165:Palladium / Q000737:chemistry; D013237:Stereoisomerism; D013449:Sulfonamides / Q000138:chemical synthesis* / Q000737:chemistry; D000096926:Benzenesulfonamides
D007555:Isoxazoles; D010165:Palladium; D013449:Sulfonamides; C406224:valdecoxib; D000096926:Benzenesulfonamides