Direct conversion from alkenes to alkynes

Alkynes are widely used as feedstock chemicals and functional groups in organic chemistry^1,2. However, although the hydrogenation from an alkyne to an alkene is well established, typical methods for the reverse reaction-conversion of an alkene to an alkyne-are based on elimination chemistry reported in the 1860s³ and use forcing conditions (strong base or high temperatures)^4-6. This precludes more general application on functional molecules. Here we report a recyclable selenanthrene reagent that mediates alkenes desaturation to alkynes under mild conditions. This method shows broad compatibility with both classical leaving groups and sensitive functional groups, enabling application late-stage in the efficient synthesis of complex alkynes. Moreover, this platform enables Z/E alkenes configuration inversion or sorting that are inaccessible with existing methods, highlighting its potential for diverse downstream derivatizations.