HFIP-promoted phosphorylation of indol-3-yl methanols to access (indol-3-yl)methyl phosphonates†

The Michaelis–Arbuzov reaction is a widely used method to convert alkyl halides into phosphonates and their derivatives, which are valuable organic molecules. The alcohol-based Michaelis–Arbuzov reaction acts as an appealing approach with a variety of advantages. We report herein the metal-free phosphorylation of indol-3-yl methanol substrates promoted by 1,1,1,3,3,3-hexafluoroisopropanol (HFIP). The reaction demonstrates a wide substrate scope and functional group tolerance and also displays powerful generality for the synthesis of (indol-3-yl)methyl phosphonates. Mechanistically, HFIP serves as both an acid to promote dehydration and a nucleophile to progress the phosphonate-forming step.