Science of Synthesis

Paterson, A. J.; Beke-Somfai, T.; Kann, N., Science of Synthesis: Click Chemistry, (2021) 1, 290.

Fokin and co-workers were amongst the first to elucidate a catalytic cycle for the RuAAC reaction through a combination of experimental and DFT studies.[‌15‌] They proposed that the reactive catalytic species was based on the Ru(Cp*)Cl core, with the observation that ruthenium complexes lacking both the pentamethylcyclopentadienyl and chloro ligands performed comparatively poorly. The azide and alkyne reactants can exchange with spectator ligands and then oxidatively couple with each other to form a ruthenacycle ‌2‌ (‌Scheme 3‌). DFT calculations showed that this step is, in essence, a nucleophilic attack of the alkyne onto the terminal electrophilic nitrogen, and steric and electronic factors in this step are responsible for the dominant 1,5-selectivity. The metallacycle intermediate then undergoes a rate-determining reductive elimination to form the triazole product, which can then exchange with spectator ligands to regenerate the active catalyst.

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‌Meeeee 8‌ Meeeeeeee Meeeeeee ee eee Meeeeeee eeeee eee Meeeee Meeeee Meeeeee Meeeeeee Meeee MMM Meeeeeeeeeee (Meeeeeee Meeeeeee Meeee ee eeee · eee−8)[‌88‌]

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References