Reactions of alkynes- copper-catalyzed cyclization of functionalized alkynes with elemental sulfur/selenium to form oxathiines/oxaselenines

Abstract

In this article, a part of the work related to the reactivity of alkynes from our group will be highlighted. These include (i) [Pd]-catalyzed double arylation and phosphonylation of phosphonoalkynes, (ii) Ruthenium catalyzed insertion of alkyne into aromatic amides/amines that involves C-H activation, (iii) [Pd]- or [Cu]-catalyzed cyclization reactions of ynamides, (iv) [Cu]-catalyzed click and intramolecular arylation and (v) [Cu]-catalyzed cyclization of functionalized alkynes with elemental sulfur/selenium. While the first four topics relate to our previous work, under the last topic, an efficient [Cu]-catalyzed tandem-cyclization of 1-iodo-(2-((3-aryl-prop-2-yn-1-yl)oxy)benzene to generate oxathiines/oxaselenines by the insertion of elemental sulfur/selenium in a regio- and stereo-specific manner via a 6 exo-dig cyclization is achieved. Deuterium-labelling experiment demonstrates the crucial role of water as a proton source in the cyclization process. The pathway involves the one-pot intermolecular C-S/C-Se bond formation and sequential hydrothiolation/hydroselenation process.