A Multimetallic Piano-Stool Ir–Sn₃ Catalyst for Nucleophilic Substitution Reaction of γ-Hydroxy Lactams through N-Acyliminium Ions

A multimetallic piano-stool complex [Cp*Ir­(SnCl₃)₂{SnCl₂(H₂O)₂}] (1) having Ir–Sn₃ motif has been synthesized from [Cp*IrCl₂]₂ and SnCl₂. The multimetallic complex catalytically promotes the nucleophilic substitution reaction (here after α-amidoalkylation reaction) of γ-hydroxylactams generated from phthalimidals to obtain decorated isoindolinones in excellent yields. Succinamidals, however, lead to the substituted pyrrolidinones (thermodynamic control product) via S_N1-type path as well as eliminated pyrrolinones (kinetic control product) via an E1-type path, depending on the reaction parameters. A straightforward application of this methodology is to synthesize benzo-fused indolizidine alkaloid mimics.