Cyclocondensation Reaction of Mesoionic 4-Trifluoroacetyl-1,3-oxazolium-5-olates with Hydroxylamine affording 6-Trifluoromethyl-5,6-dihydro-4H-1,2,4-oxadiazin-6-ols
摘要:
Mesoionic 4-trifluoroacetyl-1,3-oxazolium-5-olates (1) undergo tandem addition of hydroxylamine to afford 6-trifluoromethyl-1,2,4-oxadiazin-6-ols (3) in high yields.
Development of an Amine-Catalyzed Regioselective Synthesis of Pyrroles
作者:Taban K. K. Kakaawla、Joseph P. A. Harrity
DOI:10.1021/acs.orglett.7b03658
日期:2018.1.5
A regioselective synthesis of pyrroles has been devised through the cycloaddition of 1,3-oxazolium-5-olates and enamines. Product regiochemistry is controlled by the enamine substitution pattern. Moreover, an amine-catalyzed variant of this reaction allows aldehydes to be used directly as substrates for pyrrolesynthesis.
Convenient Synthesis of 4-Trifluoromethyl-Substituted Imidazole Derivatives.
作者:Masami KAWASE、Setsuo SAITO、Teruo KURIHARA
DOI:10.1248/cpb.49.461
日期:——
Mesoionic 4-trifluoroacetyl-1, 3-oxazolium-5-olates (1), obtained from the reaction of N-acyl-N-alkylglycines (2) with trifluoroacetic anhydride, react with ammonia to give 4-trifluoromethyl-3, 4-dihydroimidazoles (3) in high yields. Dehydration of 3 gives 4-trifluoromethylimidazoles (4) in high yields. The novel ring transformation of 1 into 3 occurs via a regioselective attack of ammonia on the C-2 position of the ring.
Convenient Synthesis of 5-Trifluoroacetylated Imidazoles by Ring Transformation of Mesoionic 1,3-Oxazolium-5-olates.
作者:Masami KAWASE、Setsuo SAITO
DOI:10.1248/cpb.48.410
日期:——
Mesoionic 4-trifluoroacetyl-1, 3-oxazolium-5-olates (1), obtained from the reaction of N-acyl-N-alkylglycines (2) with trifluoroacetic anhydride, react with amidines to give 5-trifluoroacetylimidazoles (3) in moderate yield. The novel ring trandformations of 1 into 3 occur via an initial attack of amidines on the C-2 position of the ring.
Trialkyl phosphites were evaluated as phosphorus nucleophiles for addition to mesoionic 4-trifluoroacetyl-1,3-oxazolium-5-olates (1), thereby producing tetravalent phosphorus zwitterions (2) in good yields. The structure of 2 was determined to be...
A novel ring transformation of mesoionic 1,3-oxazolium-5-olates into 5-trifluoroacetylated and 5-perfluoroacylated imidazoles by reaction with amidines
作者:Masami Kawase
DOI:10.1039/c39940002101
日期:——
Treatment of mesoionic 1,3-oxazolium-5-olates with amidines causes a novel ring transformation affording 5-trifluoroacetyl- and 5-perfluoroacyl-imidazoles in moderate yields.