Reductive Deoxygenation of Aromatic Aldehydes and Ketones with Boron Triiodide.

Deoxygenation of carbonyls is an area of value in synthetic transformations because it allows for the traceless utilization of carbonyl chemistry, a mainstay in synthetic manipulations. Since oxygenation patterns are common in biological settings, deoxygenation can also be used to valorize biologically derived feedstocks. Herein, we describe the use of potassium borohydride and iodine, two common and benchtop-stable reagents, to generate boron triiodide in situ, which performs full deoxygenation of aryl aldehydes and ketones. For aldehydes, benzyl iodide products are formed, whereas for ketones, the fully reduced methylene is produced. Byproducts upon workup are low-toxicity boric acid and iodide salts, making the process practical and appealing for a wide range of applications.