Dealkylation Reaction of Acetals, Phosphonate, and Phosphate Esters with Chlorotrimethylsilane/Metal Halide Reagent in Acetonitrile, and Its Application to the Synthesis of Phosphonic Acids and Vinyl Phosphates

Abstract A mild and efficient method has been developed for carbon-oxygen bond cleavage using chlorotrimethylsilane/sodium iodide in acetonitrile. It was applied to synthetic transformation under nonaqueous and neutral conditions, such as acetal deprotection and the synthesis of phosphonic acids from the corresponding dialkyl phosphonates via methanolysis of their silyl esters. Effectiveness of various kinds of metal or ammonium iodides for this type of dealkylation was examined in the acetonitrile solution by 1H NMR. Satisfactory results were also obtained with lithium or potassium iodide in place of sodium iodide. However, copper(I) or quarternary ammonium iodide was ineffective. Chlorotrimethylsilane/lithium bromide in acetonitrile is effective for selective dealkylation of multifunctional phosphonic esters or dialkyl vinyl phosphates.