Phosphonic acid mediated practical dehalogenation and benzylation with benzyl halides.

For the first time, by using H 3 PO 3 /I 2 system, various benzyl chlorides, bromides and iodides were dehalogenated successfully. In the presence of H 3 PO 3 , benzyl halides underwent electrophilic substitution reactions with electron-rich arenes, leading to a broad range of diarylmethanes in good yields. These transformations feature green, cheap reducing reagents and metal-free conditions. A possible mechanism was proposed.