Titanium, while being among the most earth-abundant metals, has often been thought to be an inert for redox processes, limiting its use in organic catalysis. Our group has recently shown that the coupling of alkynes and diazenes to form multisubstituted pyrroles occurs catalytically with titanium. This reaction is not without limitations; the diazene scope is limited to aryl diazenes, and moderate amounts of competitive alkyne trimerization occurs. This has lead us to seek out alternative nitrene sources that would be reactive enough to reduce undesirable trimerization as well as improve the reaction scope. Herein, we report the use of azides in the [2+2+1] formation of pyrroles, which has allowed facile synthesis of electron-rich pentaalkyl pyrroles.

Exploring nitrene sources for the titanium-catalyzed [2+2+1] formation of pyrroles

255th National Meeting (2018)

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