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Nonheme iron-mediated amination of C(sp3)-H bonds. Quinquepyridine-supported iron-imide/nitrene intermediates by experimental studies and DFT calculations.
J Am Chem Soc. 2013 May 15; 135(19):7194-204.JA

Abstract

The 7-coordinate complex [Fe(qpy)(MeCN)2](ClO4)2 (1, qpy = 2,2':6',2″:6″,2''':6''',2''''-quinquepyridine) is a highly active nonheme iron catalyst for intra- and intermolecular amination of C(sp(3))-H bonds. This complex effectively catalyzes the amination of limiting amounts of not only benzylic and allylic C(sp(3))-H bonds of hydrocarbons but also the C(sp(3))-H bonds of cyclic alkanes and cycloalkane/linear alkane moieties in sulfamate esters, such as those derived from menthane and steroids cholane and androstane, using PhI═NR or "PhI(OAc)2 + H2NR" [R = Ts (p-toluenesulfonyl), Ns (p-nitrobenzenesulfonyl)] as nitrogen source, with the amination products isolated in up to 93% yield. Iron imide/nitrene intermediates [Fe(qpy)(NR)(X)](n+) (CX, X = NR, solvent, or anion) are proposed in these amination reactions on the basis of experimental studies including ESI-MS analysis, crossover experiments, Hammett plots, and correlation with C-H bond dissociation energies and with support by DFT calculations. Species consistent with the formulations of [Fe(qpy)(NTs)2](2+) (CNTs) and [Fe(qpy)(NTs)](2+) (C) were detected by high-resolution ESI-MS analysis of the reaction mixture of 1 with PhI═NTs (4 equiv). DFT calculations revealed that the reaction barriers for H-atom abstraction of cyclohexane by the ground state of 7-coordinate CNTs and ground state of C are 15.3 and 14.2 kcal/mol, respectively, in line with the observed high activity of 1 in catalyzing the C-H amination of alkanes under mild conditions.

Authors+Show Affiliations

Department of Chemistry and State Key Laboratory of Synthetic Chemistry, The University of Hong Kong, Pokfulam Road, Hong Kong.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article

Language

eng

PubMed ID

23634746

Citation

Liu, Yungen, et al. "Nonheme Iron-mediated Amination of C(sp3)-H Bonds. Quinquepyridine-supported Iron-imide/nitrene Intermediates By Experimental Studies and DFT Calculations." Journal of the American Chemical Society, vol. 135, no. 19, 2013, pp. 7194-204.
Liu Y, Guan X, Wong EL, et al. Nonheme iron-mediated amination of C(sp3)-H bonds. Quinquepyridine-supported iron-imide/nitrene intermediates by experimental studies and DFT calculations. J Am Chem Soc. 2013;135(19):7194-204.
Liu, Y., Guan, X., Wong, E. L., Liu, P., Huang, J. S., & Che, C. M. (2013). Nonheme iron-mediated amination of C(sp3)-H bonds. Quinquepyridine-supported iron-imide/nitrene intermediates by experimental studies and DFT calculations. Journal of the American Chemical Society, 135(19), 7194-204. https://doi.org/10.1021/ja3122526
Liu Y, et al. Nonheme Iron-mediated Amination of C(sp3)-H Bonds. Quinquepyridine-supported Iron-imide/nitrene Intermediates By Experimental Studies and DFT Calculations. J Am Chem Soc. 2013 May 15;135(19):7194-204. PubMed PMID: 23634746.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Nonheme iron-mediated amination of C(sp3)-H bonds. Quinquepyridine-supported iron-imide/nitrene intermediates by experimental studies and DFT calculations. AU - Liu,Yungen, AU - Guan,Xiangguo, AU - Wong,Ella Lai-Ming, AU - Liu,Peng, AU - Huang,Jie-Sheng, AU - Che,Chi-Ming, Y1 - 2013/05/02/ PY - 2013/5/3/entrez PY - 2013/5/3/pubmed PY - 2013/5/3/medline SP - 7194 EP - 204 JF - Journal of the American Chemical Society JO - J Am Chem Soc VL - 135 IS - 19 N2 - The 7-coordinate complex [Fe(qpy)(MeCN)2](ClO4)2 (1, qpy = 2,2':6',2″:6″,2''':6''',2''''-quinquepyridine) is a highly active nonheme iron catalyst for intra- and intermolecular amination of C(sp(3))-H bonds. This complex effectively catalyzes the amination of limiting amounts of not only benzylic and allylic C(sp(3))-H bonds of hydrocarbons but also the C(sp(3))-H bonds of cyclic alkanes and cycloalkane/linear alkane moieties in sulfamate esters, such as those derived from menthane and steroids cholane and androstane, using PhI═NR or "PhI(OAc)2 + H2NR" [R = Ts (p-toluenesulfonyl), Ns (p-nitrobenzenesulfonyl)] as nitrogen source, with the amination products isolated in up to 93% yield. Iron imide/nitrene intermediates [Fe(qpy)(NR)(X)](n+) (CX, X = NR, solvent, or anion) are proposed in these amination reactions on the basis of experimental studies including ESI-MS analysis, crossover experiments, Hammett plots, and correlation with C-H bond dissociation energies and with support by DFT calculations. Species consistent with the formulations of [Fe(qpy)(NTs)2](2+) (CNTs) and [Fe(qpy)(NTs)](2+) (C) were detected by high-resolution ESI-MS analysis of the reaction mixture of 1 with PhI═NTs (4 equiv). DFT calculations revealed that the reaction barriers for H-atom abstraction of cyclohexane by the ground state of 7-coordinate CNTs and ground state of C are 15.3 and 14.2 kcal/mol, respectively, in line with the observed high activity of 1 in catalyzing the C-H amination of alkanes under mild conditions. SN - 1520-5126 UR - https://www.unboundmedicine.com/medline/citation/23634746/Nonheme_iron_mediated_amination_of_C_sp3__H_bonds__Quinquepyridine_supported_iron_imide/nitrene_intermediates_by_experimental_studies_and_DFT_calculations_ L2 - https://doi.org/10.1021/ja3122526 DB - PRIME DP - Unbound Medicine ER -
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