Ketone-catalyzed photochemical C(sp3)–H chlorination

Abstract

Photoexcited arylketones catalyze the direct chlorination of C(sp3)–H groups by N-chlorosuccinimide. Acetophenone is the most effective catalyst for functionalization of unactivated C–H groups while benzophenone provides better yields for benzylic C–H functionalization. Activation of both acetophenone and benzophenone can be achieved by irradiation with a household compact fluorescent lamp. This light-dependent reaction provides a better control of the reaction as compared to the traditional chlorination methods that proceed through a free radical chain propagation mechanism.

Visible Light‐Induced C−H Bond Functionalization: A Critical Review

“…In 2016, a visible‐light promoted tertiary alkyl C−H chlorination in the presence of Ru(bpy) 3 Cl 2 was reported by the group of Chen . In continuation of their interest in visible light‐promoted C−H chlorination reactions, Chen and co‐workers reported the triplet aryl ketone‐catalyzed chlorination reactions of sp 3 C−H bonds in the presence of visible light …”

Pd-Catalyzed, Highly Selective C(sp2)-Br Bond Coupling Reactions of o-(or m-, or p-) Chloromethyl Bromobenzene with Arylboronic Acids

“…4- ( chloromethyl ) -1,1′-biphenyl ( 3b ) [ 27 ]: Yellow oil (47.9 mg, 79%). 1 H-NMR (400 MHz, CDCl 3 ) δ 7.58 (d, J = 7.2 Hz, 4H), 7.51–7.40 (m, 4H), 7.39–7.32 (m, 1H), 4.63 (s, 2H).…”

Electronic control over site-selectivity in hydrogen atom transfer (HAT) based C(sp3)–H functionalization promoted by electrophilic reagents

“…The acetophenone photocatalyzed halogenation of 3-methylbutanoic acid, employing Selectfluor and N-chlorosuccinimide (NCS), respectively, as the fluorine or chlorine atom donor was investigated. 98,127 With the former system exclusive formation of 3-fluoro-3-methylbutanoic acid was observed, whereas under chlorination conditions the reaction led to the formation of the products deriving from chlorination at C-3 and C-4 in a 1.8 : 1 ratio (Scheme 96).…”