Rhodium(iii)-catalyzed indole synthesis at room temperature using the transient oxidizing directing group strategy.

Rh-catalyzed reactions of N-alkyl anilines with internal alkynes at room temperature have been developed using an in situ generated N-nitroso group as a transient oxidizing directing group. Due to mild reaction conditions, this method enabled synthesis of a broad range of N-alkyl indoles, including even two indole-based medicinal compounds. Our work disclosed the feasibility of the transient oxidizing directing group strategy in C-H functionalization reactions, which possesses the potential to enhance overall step-economy and impart new reactivity patterns to substrates.

Dehydrogenative desaturation-relay via formation of multicenter-stabilized radical intermediates.

In organic molecules, the reactivity at the carbon atom next to the functional group is dramatically different from that at other carbon atoms. Herein, we report that a versatile copper-catalyzed method enables successive dehydrogenation or dehydrogenation of ketones, aldehydes, alcohols, α,β-unsaturated diesters, and N-heterocycles to furnish stereodefined conjugated dienecarbonyls, polyenecarbonyls, and nitrogen-containing heteroarenes. On the basis of mechanistic studies, the copper-catalyzed successive dehydrogenation process proceeds via the initial α,β-desaturation followed by further dehydrogenative desaturation of the resultant enone intermediate, demonstrating that the reactivity at α-carbon is transferred through carbon-carbon double bond or longer π-system to the carbon atoms at the positions γ, ε, and η to carbonyl groups.

[Cu]-catalyzed domino Sonogashira coupling followed by intramolecular 5-exo-dig cyclization: synthesis of 1,3-dihydro-2-benzofurans.

An efficient [Cu]-catalyzed domino Sonogashira coupling of o-bromobenzyl tertiary alcohols with terminal aryl acetylenes followed by an intramolecular anti-5-exo-dig cyclization is presented. The terminal aryl acetylenes were identified as ideal coupling partners that permit in situ intramolecular oxacyclization by the hydroxyl group as a pre-existing nucleophile of the alcohol. Notably, the intramolecular nucleophilic attack of the hydroxyl group took place on the alkyne moiety in a highly regio- and stereoselective manner.