ChemInform Abstract: Asymmetric 1,3‐Dipolar Cycloaddition of Nitrones with Ketene Acetals Catalyzed by Chiral Oxazaborolidines.

Abstract

1994 stereochemistry stereochemistry (general, optical resolution) O 0030 -038Asymmetric 1,3-Dipolar Cycloaddition of Nitrones with Ketene Acetals Catalyzed by Chiral Oxazaborolidines.-The nitrones (III) or (VI) and ketene acetals (II) or (VII) undergo an asym. 1,3-dipolar cycloaddition in the presence of catalytic oxazaborolidines (I) and (V). The resulting isoxazolidines are obtained in high yield and regioselectivity but, in general, with low enantioselectivity. Mild hydrogenolysis of the cycloadducts affords suitable synthons for imporant classes such as the isoquinoline (VIII), intermediate for biologically active compounds. -(SEERDEN, J.-P. G.; SCHOLTE OP REIMER, A. W. A.; SCHEEREN, H. W.; Tetrahedron Lett. 35 (1994) 25, 4419-4422; Dep. Org. Chem., Univ. Nijmegen, NL-6525 ED Nijmegen, Neth.; EN)