Multi‐Pathway Consequent Chemoselectivities of CpRuCl(PPh(3))(2)/MeI‐Catalysed Norbornadiene Alkyne Cycloadditions

Chemoselectivities of five experimentally realised CpRuCl(PPh(3))(2)/MeI‐catalysed couplings of 7‐azabenzo‐norbornadienes with selected alkynes were successfully resolved from multiple reaction pathway models. Density functional theory calculations showed the following mechanistic succession to be energetically plausible: (1) CpRuI catalyst activation; (2) formation of crucial metallacyclopentene intermediate; (3) cyclobutene product (P2) elimination (ΔG (Rel(RDS))≈11.9–17.6 kcal mol(−1)). Alternative formation of dihydrobenzoindole products (P1) by isomerisation to azametalla‐cyclohexene followed by subsequent CpRuI release was much less favourable (ΔG (Rel(RDS))≈26.5–29.8 kcal mol(−1)). Emergent stereoselectivities were in close agreement with experimental results for reactions a, b, e. Consequent investigations employing dispersion corrections similarly support the empirical findings of P1 dominating in reactions c and d through P2→P1 product transformations as being probable (ΔG≈25.3–30.1 kcal mol(−1)).