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Photoexcited Pd(ii) auxiliaries enable light-induced control in C(sp3)–H bond functionalisation† † Electronic supplementary information (ESI) available. CCDC 1965101. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c9sc05722f

ABSTRACT: Herein we report the photophysical and photochemical properties of palladacycle complexes derived from 8-aminoquinoline ligands, commonly used auxiliaries in C–H activation. Spectroscopic, electrochemical and computational studies reveal that visible light irradiation induces a mixed LLCT/MLCT charge transfer providing access to synthetically relevant Pd(iii)/Pd(iv) redox couples. The Pd(ii) complex undergoes photoinduced electron transfer with alkyl halides generating C(sp3)–H halogenation products rather than C–C bond adducts. Online photochemical ESI-MS analysis implicates participation of a mononuclear Pd(iii) species which promotes C–X bond formation via a distinct Pd(iii)/Pd(iv) pathway. To demonstrate the synthetic utility, we developed a general method for inert C(sp3)–H bond bromination, chlorination and iodination with alkyl halides. This new strategy in auxiliary-directed C–H activation provides predictable and controllable access to distinct reactivity pathways proceeding via Pd(iii)/Pd(iv) redox couples induced by visible light irradiation. Visible light irradiation of 8-aminoquinoline Pd(ii) complexes initiates photoinduced electron transfer with alkyl halides, affording C–H halogenation over C–C bond adducts. A method for inert C(sp3)–H bond halogenation (Br, Cl and I) is reported.

SUBMITTER: Czyz M

PROVIDER: S-EPMC8157331 | biostudies-literature |

REPOSITORIES: biostudies-literature

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