Electronically Mediated Selectivity in Ring Opening of 1-Azirines. The 3-<i>Z</i> Mode: Convenient Route to 2-Aza-1,3-dienes
作者:Marcia T. Barroso、Albert Kascheres
DOI:10.1021/jo980198u
日期:1999.1.1
Reaction of 1-azirine-3-methylacrylates 1a,b with imidazoles and pyrazoles under mild conditions results in the formation of 2-aza-1,3-dienes 2a-g containing a potential leaving group at the 1-position. Simple alcohols (methanol and ethanol) react similarly with la,b in the presence of sodium carbonate to afford 2h-j. Utilization of 2 in the hetero Diels-Alder reaction with electron-deficient dienophiles is described.
Reaction of methyl (E)-2-phenyl-1-azirine-3-acrylates with hydrazines and amidines. Synthetic and mechanistic implications
作者:Albert Kascheres、Cecilia M. A. Oliveira、Mariangela B. M. De Azevedo、Cintia M. S. Nobre
DOI:10.1021/jo00001a004
日期:1991.1
1-Azirines 2a-b react with hydrazine in methanol to produce hexahydropyrrolo[3,2-c]pyrazol-5-ones 3a-b. The process is suggested to involve intramolecular interception of an unstable 4-aminopyrazoline intermediate resulting from C=N bond cleavage. Reaction of 2a with phenylhydrazine similarly affords 3c. In dimethyl sulfoxide, on the other hand, formamidine, guanidine, and hydrazine afford imidazole 4, pyrimidines 5a-b, amino-s-triazine 6, or triazole 9 as a consequence of C-C bond cleavage in aziridine intermediate 8. The intermediacy of tautomers is proposed to account for the diversity of products in this case.
KASCHERES, ALBERT;OLIVEIRA, CECILIA M. A.;DE, AZEVEDO MARIANGELA B. M.;NO+, J. ORG. CHEM., 56,(1991) N, C. 7-9
作者:KASCHERES, ALBERT、OLIVEIRA, CECILIA M. A.、DE, AZEVEDO MARIANGELA B. M.、NO+
DOI:——
日期:——
Reaction of a 1-azirine-3-methylacrylate and derivatives with diphenylketene. A convenient route to 5-pyrrolin-2-ones
作者:Albert Kascheres、José Nunes、Fernando Brandão
DOI:10.1016/s0040-4020(97)00388-8
日期:1997.5
Reaction of 1-azirines 1a-d with diphenylketene afforded 1:1 adducts that were shown to be 5-pyrrolin-2-ones 3a-d. Some transformations of 3 are described.