-selective C-H arylation of phenols with -carboxyindoles under Brønsted acid- or Cu(i)-catalysis.

Control over chemo- and regioselectivity is a critical issue in the heterobiaryl synthesis C-H oxidative coupling. To address this challenge, a strategy to invert the normal polarity of indoles in the heterobiaryl coupling was developed. With -carboxyindoles as umpoled indoles, an exclusively -selective coupling with phenols has been realized, employing a Brønsted acid- or Cu(i)-catalyst (as low as 0.