PIFA-mediated oxidative cyclization of 1-carbamoyl-1-oximylcycloalkanes: synthesis of spiro-fused pyrazolin-5-one N-oxides.
A convenient and efficient synthesis of spiro-fused pyrazolin-5-one N-oxides starting from readily available 1-carbamoyl-1-oximylcycloalkanes is developed. This general protocol features a novel and facile way for access to the five-membered azaheterocycles by formation of a new N-N single bond. The key cyclization step utilizes the formation of an N-oxonitrenium intermediate, mediated by the hypervalent iodine reagent PIFA, and its subsequent intramolecular trapping by the amide moiety under rather mild experimental conditions.
Wang
Kewei
K
Department of Chemistry, Northeast Normal University, Changchun, 130024, China.
Fu
Xiaolan
X
Liu
Jinying
J
Liang
Yongjiu
Y
Dong
Dewen
D
D000473:Alkanes / Q000737:chemistry*; D003500:Cyclization; D005463:Fluoroacetates; D007462:Iodobenzenes; D008958:Models, Molecular; D015394:Molecular Structure; D047069:Pyrazolones / Q000138:chemical synthesis* / Q000737:chemistry; D013141:Spiro Compounds / Q000138:chemical synthesis* / Q000737:chemistry; D014269:Trifluoroacetic Acid / Q000737:chemistry
D000473:Alkanes; D005463:Fluoroacetates; D007462:Iodobenzenes; D047069:Pyrazolones; D013141:Spiro Compounds; C517666:phenyliodine(III) bis(trifluoroacetate); D014269:Trifluoroacetic Acid