Total Regio- and StereoselectiveSynthesis of Perhydropyrrolo[3,4-c]pyrazole Derivativesby [3+2] Intramolecular Dipolar CycloadditionReaction on Chiral Perhydro-1,3-benzoxazines
A Novel Synthesis of Enantiopure Octahydropyrrolo[3,4-b]pyrroles by Intramolecular [3 + 2] Dipolar Cycloaddition on Chiral Perhydro-1,3-benzoxazines
摘要:
[GRAPHIC]Condensation of N-substituted glycines with chiral 3-allyl-2-formyl perhydro-1,3-benzoxazines forms an azomethine ylide that cyclizes to give octahydropyrrolo[3,4-b]pyrrole derivatives. The [3 + 2] dipolar cycloadditions are stereoespecific leading to a single diastereoisomer. The chemical yields are dependent on the reaction temperature and the presence or absence of a base.
An Efficient and Diastereoselective Intramolecular 1,3-Dipolar Cycloaddition of Cyclic Azomethine Ylides and Nitrones
作者:Rafael Pedrosa、Celia Andrés、Javier Nieto、Cristóbal Pérez-Cuadrado、Iván San Francisco
DOI:10.1002/ejoc.200600242
日期:2006.7
Nitrones and azomethine ylides formed by condensation of chiral 2-formyl-perhydro benzoxazines and N-substituted hydroxylamines or cyclic α-amino acids cyclize intramolecularly yielding polycyclic isoxazolidine or pyrrolidine derivatives, respectively, with total diastereoselectivity. On the con
Diastereoselective Yang Photocyclization Reactions in Solution. Synthesis of Enantiopure Azetidin-3-ol Derivatives
作者:Rafael Pedrosa、Celia Andrés、Javier Nieto、Soledad del Pozo
DOI:10.1021/jo0481497
日期:2005.2.1
Chiral 2-acyl-3-allyl- or 2-acyl-3-benzyl-substituted perhydro-1,3-benzoxazines readily cyclized under irradiation to azetidin-3-ol derivatives. The diastereoselectivity of the cyclization is dependent on the nature of the substituents at the nitrogen atom. N-allyl-substituted derivatives yielded only two of the four possible diastereomers in moderate to good diastereomeric excess. The cyclization
A Novel Synthesis of Enantiopure Octahydropyrrolo[3,4-b]pyrroles by Intramolecular [3 + 2] Dipolar Cycloaddition on Chiral Perhydro-1,3-benzoxazines
作者:Rafael Pedrosa、Celia Andrés、Laura de las Heras、Javier Nieto
DOI:10.1021/ol0261377
日期:2002.7.1
[GRAPHIC]Condensation of N-substituted glycines with chiral 3-allyl-2-formyl perhydro-1,3-benzoxazines forms an azomethine ylide that cyclizes to give octahydropyrrolo[3,4-b]pyrrole derivatives. The [3 + 2] dipolar cycloadditions are stereoespecific leading to a single diastereoisomer. The chemical yields are dependent on the reaction temperature and the presence or absence of a base.
Total Regio- and StereoselectiveSynthesis of Perhydropyrrolo[3,4-<i>c</i>]pyrazole Derivativesby [3+2] Intramolecular Dipolar CycloadditionReaction on Chiral Perhydro-1,3-benzoxazines
Reaction of N-acyl-N′-methyl- or N-acyl-N′-phenylhydrazines with chiral 3-allyl-2-formylperhydro-1,3-benzoxazines form azomethine imines that cyclize to give perhydropyrrolo[3,4-c]pyrazole derivatives. The dipolar cycloaddition was totally regio- and stereoselective yielding a single diastereoisomer. The reaction conditions and the yields of the final compounds are dependent on the substitution pattern of the olefinic bond