Stereochemisty of 1, 3-Dipolar Cycloadditions of Nitrones with (E)-1-Alkyl-2-nitroethenes

Abstract

1, 3-Dipolar cycloadditions of the C-aryl-N-alkylnitrones 2a-c and the C, N-dialkylnitrones 2e-g with the (E)-1-alkyl-2-nitroethenes 1a, b afforded predominantly or exclusively the cis-3-substituted 4-nitroisoxazolidines 3a-d and 3f-h. Exceptions are the reactions of C-phenyl-N-isopropylnitrone (2d) and C, N-diisopropylnitrone (2h) with 1a which gave the 3, 4-trans isomers 4e and 4i as the major products. These results can be rationalized in terms of secondary orbital interactions and steric effect.