24932-57-8Relevant academic research and scientific papers
Ketenimine Formation Catalyzed by a High-Valent Cobalt Carbene in Bulky Alkoxide Ligand Environment
Grass, Amanda,Dewey, Nicholas S.,Lord, Richard L.,Groysman, Stanislav
, p. 962 - 972 (2019)
High-valent cobalt carbene Co(OR)2(CPh2) (OR = OCtBu2Ph) undergoes reaction with various isocyanides CNR (CNR = 2,6-dimethylphenyl isocyanide, 4-methoxyphenyl isocyanide, 2-chloro-6-methylphenyl isocyanide, adamantyl isocyanide) to yield the corresponding ketenimine. The reaction is accompanied by the formation of cobalt bis(alkoxide) bis(isocyanide) complexes Co(OR)2(CNR)2, which were independently synthesized and characterized. DFT calculations suggest the mechanism proceeds through isocyanide binding to Co, followed by intramolecular insertion into the Co-carbene bond to form the ketenimine. We have also conducted an investigation of the catalytic formation of ketenimines at room temperature using mixtures of diazoalkanes (diphenyldiazomethane, methyl diazo(phenyl)acetate, and ethyl diazoacetate) and isocyanides (2,6-dimethylphenyl isocyanide, 4-methoxyphenyl isocyanide, adamantyl isocyanide, cyclohexyl isocyanide, and benzyl isocyanide). While no catalytic reactivity was observed for diphenyldiazomethane, ester-substituted diazoalkanes (diazoesters) demonstrate catalytic turnover. Relatively high yields are observed for the reactions involving bulkier aliphatic substrates adamantyl and cyclohexyl isocyanides. Mechanistic studies suggest that the lack of catalytic reactivity involving diphenyldiazomethane results from the inability of Co(OR)2(CNR)2 to undergo carbene formation upon reaction with N2CPh2. In contrast, facile reaction is observed between Co(OR)2(CNR)2 and diazoesters, which enables the overall catalytic reactivity.
Hydroalumination of Ketenimines and Subsequent Reactions with Heterocumulenes: Synthesis of Unsaturated Amide Derivatives and 1,3-Diimines
Jin, Xing,Willeke, Matthias,Lucchesi, Ralph,Daniliuc, Constantin-Gabriel,Fr?hlich, Roland,Wibbeling, Birgit,Uhl, Werner,Würthwein, Ernst-Ulrich
, p. 6062 - 6075 (2015/06/30)
The series of differently substituted ketenimines 1 was hydroluminated using di-iso-butyl aluminum hydride. For the sterically congested ketenimine 1a, preferred hydroalumination of the C=N-bond was proven by X-ray crystallography (compound 5a). In situ treatment of the hydroaluminated ketenimines 5 with various heterocumulenes like carbodiimides, isocycanates, isothiocyanates and ketenimines as electrophiles and subsequent hydrolytic workup resulted in novel enamine derived amide species in case of N-attack (sterically less hindered ketenimines) under formation of a new C-N-bond or in 1,3-diimines by C-C-bond-formation in case of bulky substituents at the ketenimine-nitrogen atom. Furthermore, domino reactions with more than 1 equiv of the electrophile or by subsequent addition of two different electrophiles are possible and lead to polyfunctional amide derivatives of the biuret type which are otherwise not easily accessible.
