Stereoselective Iodocyclopropanation of Terminal Alkenes with Iodoform, Chromium(II) Chloride, and <i>N</i>,<i>N</i>,<i>N</i>‘,<i>N</i>‘-Tetraethylethylenediamine

Chemoselectivity of a reagent for (<i>E</i>)-olefination of aldehydes derived by reduction of iodoform with chromium(II) chloride in THF changes markedly by addition of TEEDA (<i>N</i>,<i>N</i>,<i>N</i>‘,<i>N</i>‘-tetraethylethylenediamine), and <i>trans</i>-iodocyclopropanes are produced stereoselectively from terminal alkenes by treatment with the base-added reagent system. The iodocyclopropanation occurs only at terminal double bonds, and di- and trisubstituted double bonds in the same molecules remained unchanged. Such functional groups as alcohol, ether, silyl ether, ester, tertiary amine, and amide groups are compatible with the reaction conditions.