Regeneration of the Milbemycin's C2-C4 Structural Arrangement from Δ2-Milbemycin

Article abstract of DOI:10.1016/0040-4039(94)80121-5

An efficient methodology for converting Δ²-milbemycin A₄ to milbemycin A₄ is described, whereby the Δ²-isomer is initially converted to the C₂ epimer which in turn is epimerized at C₂ to its natural configuration.The key transformation is a Dess-Martin type oxidation at C₅ of the C₂ epimer in order to enhance the stability of the Δ₃-double bond and facilitate epimerization.