Synthesis of Iron Hydrides by Selective C-F/C-H Bond Activation in Fluoroarylimines and Their Applications in Catalytic Reduction Reactions

摘要

The reactions of Fe(PMe3)(4) with different 2,6-diflurophenylarylimines 1-5 were explored. Fluoroarylimines 1-3, the aryl rings of which are substituted with electron-withdrawing groups, reacted with Fe(PMe3)(4) to afford the C-H activation products 6-8. However, if the aryl rings of the fluoroarylimines were substituted with electron-donating groups, the iron hydrides 9 and 10 were obtained from the reactions of the fluoroarylimines with Fe(PMe3)(4) through C-F bond activation. In a further study, silanes, especially triethoxysilane, were found to benefit the reactions and improve the yields of the hydridoiron complexes. The three-component reaction of Fe(PMe3)(4), a fluoroarylimine, and a silane could also be utilized in reactions involving 2,6-(CH3)(2)C6H3-C(=NH)-2,6-F2C6H3 (13) and 2,6-F2C6H3-C(=NH)-C6F5 (16) to synthesize iron hydrides (15 and 18). The hydridoiron complexes could be utilized as efficient catalysts in the hydrosilylation of aldehydes and ketones. Furthermore, cinnamaldehydes were selectively reduced to the corresponding cinnamyl alcohols in high yields. The mechanism of the catalytic reduction reaction was studied extensively through operando IR spectroscopy.