Visible Light Driven and Copper-Catalyzed C(sp³)–H Functionalization of O-Pentafluorobenzoyl Ketone Oximes

Abstract

The C­(sp3)–H functionalization of O-pentafluorobenzoyl ketone oximes was implemented under visible light irradiation with copper complexes as catalysts. The reactions involve iminyl-radical-mediated intramolecular hydrogen atom transfer as the key step, with the iminyl radicals being generated via copper-effected N–O cleavage. The reaction afforded 3,4-dihydro-2H-pyrroles under the conditions of [Cu­(DPEphos)­(bcp)]­PF6 and DABCO, while γ-pentafluoro­benzoyloxy ketones were produced predominantly when [Cu­(dpp)2]­PF6 and InCl3·4H2O were used as catalysts.

Directed, Remote Dirhodium C(sp3)-H Functionalization, Desaturative Annulation, and Desaturation

“…However, newer procedures have addressed some of these issues. − In our initial optimization experiments (see the Supporting Information for other transition-metal catalysts), exposure of 5-phenylpentan-2-one O -tosyloxime to Du Bois’ catalyst [Rh 2 (esp) 2 , 2 mol %] at rt using MeOH as the solvent provided benzylic methyl ether 1 in 90% isolated yield (Table ). Notably, a similar yield was obtained with just 2 equiv of MeOH in CH 2 Cl 2 , thus opening the door for the more economic use of high value and/or less readily available nucleophiles; also, a comparable result was obtained using the latter CH 2 Cl 2 reaction conditions on a 5 mmol scale, that is, 1 (86%). Even water, despite its incompatibility with other benzylic functionalization methodology and low solubility in CH 2 Cl 2 , efficiently led to benzyl alcohol 2 .…”

Recent Advances in Non-Precious Metal Catalysis

“…The use of a bulky and electron-rich diazonium salt was crucial to achieve efficient iodine activation, presumably due to the enhanced stability of the aryl radical. Other notable advances in Cu-catalyzed reactions include the following publications: (1) Cu-catalyzed diazidation reactions; 54 (2) Diastereo-and enantioselective oxidative 1,6conjugate addition; 55 (3) C−H amination of 8-aminoquinoline-directed ferrocenes; 56 (4) Cu-catalyzed hydroxymethylation of alkynes with formic acid; 57 (5) Cu-catalyzed synthesis of indolyl benzo[b]carbazoles; 58 (6) Cu-catalyzed tandem cross-coupling and alkynylogous aldol reaction to access exocyclic α-allenols; 59 (7) Tandem Cu-and Rh-catalysis for oxidation of hydrazones and enantioselective cyclopropanation; 60 (8) Cu-catalyzed CF 2 H-substituted 2-amidofurans; 61 (9) Cu-catalyzed annulation of indolyl α-diazocarbonyl to access carbazoles; 62 (10) Cu-catalyzed enantioselective 1,2reduction of cycloalkenones; 63 (11) Cu-catalyzed enantiodivergent alkynylation of isatins; 64 (12) Cu-catalyzed β-lactam formation from oximes and methyl propiolate; 65 (13) Cucatalyzed aminosulfonylation of O-homoallyl benzimidates; 66 (14) Cu-catalyzed multicomponent trifluoromethylphosphorothiolation of alkenes; 67 (15) Cu-catalyzed chloroarylsulfonylation of styrene derivatives; 68 (16) Cu-catalyzed synthesis of 5-carboxyl-4-perfluoroalkyl triazoles; 69 (17) Crossnucleophile coupling of β-allenyl silanes with tertiary C−H bonds to access 1,3-dienes; 70 (18) Cu-catalyzed C(sp 3 )−H functionalization of O-pentafluorobenzoyl ketone oximes; 71 (19) Total regioselectivity of hydrobromination of alkenes controlled by Fe or Cu catalyst; 72 (20) Enantioselective synthesis of trifluoromethyl cyclopropylboronates by Cu catalysis; 73 (21) Cu-catalyzed asymmetric cyclization of alkenyl diynes; 74 (22) Synergistic Ir/Cu catalysis for asymmetric allylic alkylation of oxindoles; 75…”

“…Other notable advances in Cu-catalyzed reactions include the following publications: (1) Cu-catalyzed diazidation reactions; (2) Diastereo-and enantioselective oxidative 1,6-conjugate addition; (3) C–H amination of 8-aminoquinoline-directed ferrocenes; (4) Cu-catalyzed hydroxymethylation of alkynes with formic acid; (5) Cu-catalyzed synthesis of indolyl benzo­[ b ]­carbazoles; (6) Cu-catalyzed tandem cross-coupling and alkynylogous aldol reaction to access exocyclic α-allenols; (7) Tandem Cu- and Rh-catalysis for oxidation of hydrazones and enantioselective cyclopropanation; (8) Cu-catalyzed CF 2 H-substituted 2-amidofurans; (9) Cu-catalyzed annulation of indolyl α-diazocarbonyl to access carbazoles; (10) Cu-catalyzed enantioselective 1,2-reduction of cycloalkenones; (11) Cu-catalyzed enantiodivergent alkynylation of isatins; (12) Cu-catalyzed β-lactam formation from oximes and methyl propiolate; (13) Cu-catalyzed aminosulfonylation of O -homoallyl benzimidates; (14) Cu-catalyzed multicomponent trifluoromethyl­phosphorothiolation of alkenes; (15) Cu-catalyzed chloro-arylsulfonylation of styrene derivatives; (16) Cu-catalyzed synthesis of 5-carboxyl-4-perfluoroalkyl triazoles; (17) Cross-nucleophile coupling of β-allenyl silanes with tertiary C–H bonds to access 1,3-dienes; (18) Cu-catalyzed C­( sp 3 )–H functionalization of O -pentafluorobenzoyl ketone oximes; (19) Total regioselectivity of hydrobromination of alkenes controlled by Fe or Cu catalyst; (20) Enantioselective synthesis of trifluoromethyl cyclopropylboronates by Cu catalysis; (21) Cu-catalyzed asymmetric cyclization of alkenyl diynes; (22) Synergistic Ir/Cu catalysis for asymmetric allylic alkylation of oxindoles; (23) Hydrosilylation of alkynes and alkenes with Cu-photocatalysis under continuous flow conditions; (24) Cu-based water oxidation catalysts with consecutive ligand-based electron transfer; (25) Heteroleptic copper-based complexes for energy-transfer processes: E → Z isomerization and tandem photocatalytic sequences; (26) Copper-catalyzed aminoheteroarylation of unactivated alkenes through distal heteroaryl migration; (27) Copper-catalyzed syntheses of multiple functionalized allenes via three-component reaction of enynes; (28) Unified mechanistic concept of the copper-catalyzed and amide-oxazoline-directed C­(sp 2 )–H bond functionalization; (29) Cu-catalyzed C–H allylation of benzimidazoles with allenes; (30) Synthesis of 1,2-aminoalcohols through enantioselective aminoallylation of ketones by Cu-catalyzed reductive coupling; (31) Copper-catalyzed N-directed distal C­(sp 3 )–H sulfonylation and thiolation with sulfinate salts; and (32) Dehydrogenative aza-[4 + 2] cycloaddition of amines with 1,3-dienes via dual catalysis …”

PdII-Catalyzed γ-C(sp3)–H (Hetero)arylation of Ketones Enabled by Transient Directing Groups

“…γ-C­(sp 3 )–H arylation using this directing group was enabled by 2-pydrione ligands (Scheme b) . Interestingly, iminyl radical generated from α-imino-oxy acids or oxime esters effectively performed an intramolecular 1,5-HAT and forged new bonds at the γ-position (Scheme c) . However, these methods have a common limitation: extra synthetic steps are needed for the covalent installation and removal of the directing groups.…”