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Iron(0) tricarbonyl η 4 -1-azadiene complexes and their catalytic performance in the hydroboration of ketones, aldehydes and aldimines via a non-iron hydride pathway
Six iron(0) tricarbonyl complexes (1a–f) with a η 4 -1-azadiene moiety were prepared and their performance in the hydroboration of unsaturated organic compounds was investigated. All the complexes exhibit catalytic activity towards hydroboration of ketones, aldehydes and aldimines with pinacolborane...
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Published in: | Dalton transactions : an international journal of inorganic chemistry 2022-08, Vol.51 (30), p.11558-11566 |
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Main Authors: | , , , , , , , |
Format: | Article |
Language: | English |
Citations: | Items that this one cites Items that cite this one |
Online Access: | Get full text |
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Summary: | Six iron(0) tricarbonyl complexes (1a–f) with a η
4
-1-azadiene moiety were prepared and their performance in the hydroboration of unsaturated organic compounds was investigated. All the complexes exhibit catalytic activity towards hydroboration of ketones, aldehydes and aldimines with pinacolborane (HBpin) as a hydride source to lead to secondary alcohols, primary alcohols, and secondary amines, respectively, after hydrolysis of the hydroboration products. Of the iron(0) tricarbonyl complexes, complex 1e is the most robust one and was employed throughout the catalytic investigation. Its preference towards the three types of substrates is as follows: aldimines > aldehydes ≫ ketones. In total, 24 substrates were examined for the catalytic hydroboration reactivity and generally, isolation yields ranging from 40% to 95% were achieved. Mechanistic investigation suggests that the catalytic hydroboration of the substrates proceeds
via
intramolecular hydride transfer without going through an Fe–H intermediate. As indicated by
1
H NMR spectroscopic monitoring, the substrates and the borane agent bind to the iron centre and the imine N atom, respectively, which facilitates the hydride transfer by activating the B–H bond and polarizing the double bond of the substrates. |
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ISSN: | 1477-9226 1477-9234 |
DOI: | 10.1039/D2DT01673G |