Metal-Free Selective Reduction of Aromatic Alkynes and Alkenes Using Phosphonic Acid

We report a novel metal-free method for selectively reducing aromatic alkynes and alkenes by using phosphonic acid. When combined with molecular iodine, this system reduces aromatic alkynes to the corresponding (E)-alkenes and alkanes in high yields. Additionally, various aromatic alkenes can be directly reduced with comparable efficiency. This protocol features low cost, simple conditions, and the avoidance of metal catalysts.