Improved procedure for the synthesis of gem-diiodoalkanes by the alkylation of diiodomethane. scope and limitations.

Functionalized gem-diiodoalkanes are obtained in good to excellent yields by employing a convenient modified procedure for the alkylation of NaCHI2 with alkyl iodides. Complete conversion to the diiodide is reliably obtained, avoiding a problematic separation of any remaining iodide starting material. Functional group tolerance toward olefins, acetals, ethers and silyl ethers, carbamates, and hindered esters is demonstrated. The use of an excess of LiCHI2 allows complete conversion of allyl and benzyl bromides with minimal elimination from the diiodide product.