Yang Yan, Anker Mathew D, Fang Jian, Mahon Mary F, Maron Laurent, Weetman Catherine, Hill Michael S
Key Laboratory of Nonferrous Metal Chemistry and Resources Utilization of Gansu Province , School of Chemistry and Chemical Engineering , Lanzhou University , Lanzhou 730000 , PR China . Email:
Department of Chemistry , University of Bath , Bath BA2 7AY , UK . Email:
Chem Sci. 2017 May 1;8(5):3529-3537. doi: 10.1039/c7sc00117g. Epub 2017 Mar 1.
Organic isocyanates are readily converted to methyl amine products through their hydroboration with HBpin in the presence of a β-diketiminato magnesium catalyst. Although borylated amide and -,-bis(boryl)hemiaminal species have been identified as intermediates during the reductive catalysis, the overall reduction and C-O activation is metal-mediated and proposed to occur through the further intermediacy of well-defined magnesium formamidato, formamidatoborate and magnesium boryloxide derivatives. Examples of all these species have been identified and fully characterised through stoichiometric reactivity studies and the stability of the borate species leads us to suggest that, under catalytic conditions, the onward progress of the deoxygenation reaction is crucially dependent on the further activation provided by the Lewis acidic HBpin substrate. These deductions have been explored and ratified through a DFT study.
在β-二酮亚胺基镁催化剂存在下，有机异氰酸酯通过与HBpin进行硼氢化反应可轻松转化为甲胺产物。尽管在还原催化过程中已鉴定出硼化酰胺和N,N-双（硼基）半胺中间体，但整体还原和C-O活化是由金属介导的，并且推测是通过明确的镁甲酰胺基、甲酰胺基硼酸酯和硼酸镁氧化物衍生物的进一步中间体作用而发生的。通过化学计量反应性研究已鉴定并充分表征了所有这些物种的实例，并且硼酸酯物种的稳定性使我们认为，在催化条件下，脱氧反应的进一步进行关键取决于路易斯酸性HBpin底物提供的进一步活化作用。这些推论已通过密度泛函理论（DFT）研究进行了探索和验证。
