Iron-Catalyzed Alkyne Carboamination via an Isolable Iron Imide Complex

• Published in: Organometallics 2021-09, Vol.40 (17), p.2945-2950
• Main Authors: Richards, Corey A, Rath, Nigam P, Neely, Jamie M
• Format: Article
• Language: English
• ISSN: 0276-7333; 1520-6041
• DOI: 10.1021/acs.organomet.1c00454

Transition metal imide-mediated C–N bond formation is a powerful strategy for the introduction of nitrogen into organic compounds. We have discovered that the reaction of N-mesityl­(β-diketiminato)­iron imide complex tBuLFeNMes ( tBuL = 3,5-bis­(2,6-diisopropylphenylimino)-2,2,6,6-tetramethylheptyl and Mes = 2,4,6-trimethylphenyl) with a terminal alkyne substrate gives a β-alkynyl enamine product by a novel alkyne carboamination process. Stoichiometric experiments revealed a catalyst deactivation pathway involving generation of the acetylide complex, tBuLFeCCPh, and mesityl amine (MesNH2) from the acetylene complex, tBuLFe­(HCCPh), and mesityl azide (MesN3). This reactivity is suppressed in the presence of coordinating additive 4-tert-butylpyridine ( t BuPy), likely through formation of the four-coordinate complex tBuLFe­(HCCPh)­( t BuPy). These insights were instrumental in identifying reaction conditions that allow for turnover of the iron catalyst.