An efficient C2-homologation of aromatic aldehydes via 5-hydroxyisoxazolidines

Article abstract of DOI:10.1016/S0040-4020(01)86449-8

The reaction of lithium enolate of acetaldehyde (generated by the known cycloreversion of THF in the presence of n-BuLi) with a number of aryl N-phenylnitrones affords 2-phenyl-3-aryl-5-hydroxyisoxazolidines (trans + cis) in high yields. A low conversion or no reaction at all were instead observed with some N-alkylnitrones (methyl and t-butyl, respectively). Base (or acid) induced decomposition of 5-hydroxyisoxazolidines allows cinnamaldehydes to be obtained in high yields. Thus the combination of the synthesis and decomposition of 5-hydroxyisoxazolidines provides a new efficient way for the C₂-homologation of aromatic aldehydes.