Total Regio- and StereoselectiveSynthesis of Perhydropyrrolo[3,4-c]pyrazole Derivativesby [3+2] Intramolecular Dipolar CycloadditionReaction on Chiral Perhydro-1,3-benzoxazines
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
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