A convenient and efficient one-pot O-alkylation of oximes from
alcohols using triphenylphosphine in carbon tetrachloride is described.
In this method, treatment of alcohols with a mixture of triphenylphosphine,
carbon tetrachloride, oxime, and DBU in the presence of catalytic
amounts of tetrabutylammonium iodide in refluxing acetonitrile regioselectively
furnishes the corresponding O-alkyl ethers
in good yields. This methodology is highly efficient O-alkylation
of oximes with various structurally diverse alcohols. Semiempirical
quantum-mechanic calculations (AM1) for unsymmetrical oxime ethers,
indicated a lower heat of formation for Z-isomers.
oxime - alcohol - O-alkylation - triphenylphosphine - carbon tetrachloride - DBU