The Uranyl Cation as a Visible‐Light Photocatalyst for C(sp³)−H Fluorination

Abstract

The fluorination of unactivated Csp3–H bonds remains a desirable, challenging transformation for pharmaceutical, agricultural, and materials scientists. Previous methods for this transformation have used bench-stable fluorine atom sources; however, many still rely on the use of UV-active photocatalysts for the requisite high-energy hydrogen atom abstraction event. Herein, we describe the use of uranyl nitrate hexahydrate as a convenient, hydrogen atom abstraction catalyst that can mediate fluorinations of certain alkanes upon activation with visible light.

Visible‐Light Photocatalysis as an Enabling Tool for the Functionalization of Unactivated C(sp3)‐Substrates

“…Recently, Sorensen and coworkers demonstrated that uranyl nitrate hexahydrate was a competent hydrogen abstraction catalyst for the visible-lightmediated fluorination of C-H bonds. [94] Although the scope was limited to the fluorination of hydrocarbons, it provides a starting point for the further development of uranium-based catalysts. …”

Selective Late‐Stage Oxygenation of Sulfides with Ground‐State Oxygen by Uranyl Photocatalysis

“…First, the strong interaction between the 2p orbital of oxygen and the 5f and 6d primary valence shells of uranium make the ground state and excited state of UO 2 2+ chemically inert to oxygen molecules, [20] which might help to prevent undesired transformations caused by active oxygen species (Scheme 1b,l eft). [23] However,w ep hrased af ew hypotheses after detailed examination. [23] However,w ep hrased af ew hypotheses after detailed examination.…”

Controlled Photocatalytic Hydrocarbon Oxidation by Uranyl Complexes

“…nitrate and carbonate), causing these reactions to be unselective . Recently, however, Sorensen and co‐workers reported the first use of photo‐excited uranyl in the selective fluorination of cycloalkanes in organic media (Scheme ) . Judicious choice of both organic solvent (CD 3 CN or acetone‐D 6 ) and anion (nitrate vs .…”

“…[7] Recently, however, Sorensen and co-workers reported the first use of photo-excited uranyl in the selective fluorination of cycloalkanes in organic media (Scheme 1). [8] Judicious choice of both organic solvent (CD 3 CN or acetone-D 6 ) and anion (nitrate vs. acetate) were crucial, and recent quantum mechanical calculations highlighted the complex interplay of singlet and triplet excited states in the reaction coordinate. [9] Subsequently, Azam and co-workers used a chiral salen 1 ligand to saturate the uranyl equatorial coordination plane, resulting in a photoactive complex that acts as a catalyst for the αcyanation of anilines (Scheme 1); [10] in this case, commercially available uranyl acetate, [U VI O 2 (OAc) 2 (OH 2 ) 2 ], shows no activity.…”