Bis(imino)acenaphthene (BIAN)-Supported N-Heterocyclic CarbenePalladium Complexes with Ancillary Ligands: Readily ActivatedPrecatalysts for Direct C-H Arylation of Thiophenes

摘要

We report herein a highly efficient direct C-H arylation ofthiophenes with (hetero)aryl bromides by bulky bis(imino)acenaphthene (BIAN)-supportedN-heterocyclic carbene palladium complexes. The relationship betweenthe structure of palladium complexes with ancillary ligands and catalytic propertieswas discussed. Upon a low palladium loading of 0.01-0.05 mol %, the bulkypalladium complex was successfully used to catalyze the cross-coupling of a variety ofthiophens with (hetero)aryl bromides under aerobic conditions. Furthermore, itprovides a practical and straightforward access to poly(3-hexylthiophenes) with highmolecular weight and high HT value under aerobic reaction conditions. To accessthe mechanistic of the transformation, experiment investigation and DFTcalculations on the direct arylationwere performed, which supported theinvolvement of a Pd(0)/Pd(II)CMD process.

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