Ruthenium-catalyzed C(sp²)–H <i>ortho</i>-heteroarylation of 2-arylphthalazin-1(2<i>H</i>)-one using five-membered heteroarenes by cross-dehydrogenative coupling

The cross-dehydrogenative coupling reactions have gained supreme importance owing to their synthetic efficiency in accessing simple to complex organic molecules. Herein, we report a Ru(II)-catalyzed directing group-assisted CDC reaction between 2-arylphthalazin-1(2<i>H</i>)-one and heteroarenes. This methodology offers advantages such as excellent regio-selectivity with good functional group compatibility, resulting in a broad substrate scope. Mechanistically, Ru(II)-catalyzed <i>ortho</i>-C(sp²)-H cross-coupling operates <i>via</i> a concerted metalation-deprotonation (CMD) mechanism.