title: Fluoride-Catalyzed Methylation of Amines by Reductive Functionalization of CO2with Hydrosilanes.
abstract: An effective and inexpensive organocatalyst tetrabutylammonium fluoride (TBAF) was developed for the reductive functionalization of CO2with amines to selectively afford formamides or methylamines by employing hydrosilanes. Hydrosilanes with different substituents show discriminatory reducing activity. Thus, the formation of formamides and further reduction products, that is, methylamines could be controlled by elegantly tuning hydrosilane types. Formamides were obtained exclusively under an atmospheric pressure of CO2with triethoxysilane. Using phenylsilane as a reductant, methylamines were attained with up to 99 % yield at 50 °C coupled to a complete deoxygenation of CO2. The crucial intermediate silyl formate in the formylation step was identified and thereby a tentative mechanism involving the fluoride-promoted hydride transfer from the hydrosilane to CO2/formamide was proposed. Striking features of this metal-free protocol are formylation and methylation of amines by reductive functionalization of CO2with hydrosilanes and mild reaction conditions.
authors.affiliation: State Key Laboratory and Institute of Elemento-organic Chemistry, Nankai University, Tianjin, 300071, P. R. China.
authors.forename: Xiao-Fang
authors.initials: XF
authors.lastname: Liu
authors.affiliation: State Key Laboratory and Institute of Elemento-organic Chemistry, Nankai University, Tianjin, 300071, P. R. China.
authors.forename: Ran
authors.initials: R
authors.lastname: Ma
authors.affiliation: State Key Laboratory and Institute of Elemento-organic Chemistry, Nankai University, Tianjin, 300071, P. R. China.
authors.forename: Chang
authors.initials: C
authors.lastname: Qiao
authors.affiliation: State Key Laboratory and Institute of Elemento-organic Chemistry, Nankai University, Tianjin, 300071, P. R. China.
authors.forename: Han
authors.initials: H
authors.lastname: Cao
authors.affiliation: State Key Laboratory and Institute of Elemento-organic Chemistry, Nankai University, Tianjin, 300071, P. R. China. heln@nankai.edu.cn.|Collaborative Innovation Center of Chemical Science and Engineering, Nankai University, Tianjin, 300071, P. R. China. heln@nankai.edu.cn.
authors.forename: Liang-Nian
authors.identifier: http://orcid.org/0000-0002-6067-5937
authors.initials: LN
authors.lastname: He
keywords: carbon dioxide fixation; chemoselectivity; hydrosilanes; organocatalysis; reductive functionalization