Reduction of acetals with samarium diiodide in acetonitrile in the presence of Lewis acids

Transformation of acetals into ethers by partial reduction using a samarium diiodide-lewis acids-acetonitrile system is described. The reaction with a romatic acetals occurred in good yields in the presence of aluminum chlorid e (2 eq) whereas the corresponding aliphatic, vinylic, and alkynyl derivati ves did not afford ethers under the same conditions. beta -Elimination to g ive an enol ether becomes predominant when aliphatic acetals that possess a hydrogen at the 2-position are treated with iodotrimethylsilane in the pre sence of SmI2 or SmI3.