A novel method for the stereospecificsynthesis of 1,5-disubstituted tetrazoles from ketoximes via the Beckmann rearrangement was developed using diphenyl phosphorazidate (DPPA) as both the oxime activator and azide source. Various ketoximes were transformed into the corresponding 1,5-disubstituted tetrazoles with exclusive trans-group migration and no E-Z isomerization of the ketoxime. This method
method for synthesis of oximes from aldehydes or ketones with N-hydroxyphthalimide or N-hydroxysuccinimide in water has been described. It is the first time to utilize NHPI as an oximation reagent to synthesize aldoximes and ketoximes from the corresponding organic carbonyl compounds without other reagents. The reaction tolerates various functional groups and affords the corresponding oximes in 76%–98% yields
Isomerization of oxime derivatives was researched in detail to find out the methods for the syn-anti isomerization of O-substituted oximes. Based on these findings were developed simple methods for the preparation of aza-heterocycles from both stereoisomers of oximes. Quinolines were synthesized from β-aryl ketone oximes by treatment with trifluoroacetic anhydride and 4-chloranil. γ,δ-Unsaturated O-methoxyacetyloximes were transformed to 2H-dihydropyrroles by reaction with methoxy-acetic acid.
Beckmann Rearrangement of Oximes Catalyzed with Tetrabutylammonium Perrhenate and Trifluoromethanesulfonic Acid
作者:Hiroyuki Kusama、Yuko Yamashita、Koichi Narasaka
DOI:10.1246/bcsj.68.373
日期:1995.1
The Beckmannrearrangement of oximes is catalyzed by a combined use of tetrabutylammonium perrhenate (Bu4NReO4) and trifluoromethanesulfonic acid in nitromethane under azeotropic conditions, giving amides in high yield. By employing this catalytic system, amides can be prepared directly from ketones and hydroxylamine hydrochloride.
Three component hydroxyletherification and hydroxylazidation of (trifluoromethyl)alkenes: access to α-trifluoromethyl β-heteroatom substituted tertiary alcohols
The three component hydroxyletherification and hydroxylazidation reactions of (trifluoromethyl)alkenes are reported, providing various useful α-trifluoromethyl β-heteroatom substituted tertiary alcohols in high yields.