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DOI number:10.1002/chem.201302140

Journal:Chemistry – A European Journal

Key Words:C-H activation; cross-dehydrogenative coupling; dehydrogenation; homogeneous catalysis; palladium

Abstract:We reported herein a dehydrogenative C-H/C-H crosscoupling that selectively addresses the C7 position of indolines. The palladium(II) catalysis requires TFA as an additive and Na2S2O8 as the terminal oxidant. An acetyl group at the indoline nitrogen atom was employed as a directing group, no such group was required at the arene coupling partner. Remarkably, the amide group alone is not sufficient to allow for C-H bond activation at C7. An additional substituent at C2 was identified as a crucial factor, enabling selective arylation at C7. We believe that steric repulsion between that substituent and the amide group forces the amide oxygen atom into the proximity of the hydrogen atom at C7, thereby facilitating C-H bond activation in this position. Our hypothesis is supported by 1H NMR spectroscopic analysis of several indolines where line broadening and deshielding of that hydrogen atom is only seen for those indolines that eventually undergo C7-selective CH arylation.

Indexed by:Journal paper

Discipline:Natural Science

First-Level Discipline:Chemistry

Document Type:J

Volume:19

Page Number:10845–10848

Translation or Not:no

Included Journals:SCI、EI、SSCI

First Author:Lin-Yu Jiao