ChemInform Abstract: Nitrobenzene as a Monodentate (O) and Bidentate (O,O′) Ligand: Synthesis and Structures of Zn(PhNO2)n(OTeF5)2 (n = 2,3).

Hurlburt, Paul K.; Kellett, Patti J.; Anderson, Oren P.; Strauss, Steven H.

doi:10.1002/chin.199041256

Cited by 1 publication

(1 citation statement)

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“…15 Coordination of nitroarene 12 to 17 produces 18 or 19 depending on whether the acetate is directly coordinated to iron. 16 We anticipate that hydride transfer to the nitro-group occurs via transition state TS-20, where the iron-hydride bond breaks simultaneously with nitrogen-hydrogen bond formation. The resulting iron species (κ 1 -or κ 2 -coordinated) 17 fragments to produce nitrosoarene 22 and iron hydroxide 23.…”

Section: Fe-catalyzed Indole Synthesismentioning

confidence: 98%

The Development and Mechanistic Study of an Iron-Catalyzed Intramolecular Nitroso Ene Reaction of Nitroarenes

Vu,

Powell,

Ford

et al. 2023

Preprint

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An intramolecular iron-catalyzed nitroso ene reaction was developed to afford six- or seven-membered N-heterocycles from nitroarenes using an earth abundant iron catalyst and phenylsilane as the terminal reductant. The reaction can be triggered using as little as 3 mol % of iron(II) acetate and 3 mol % of 4,7-dimethoxyphenanthroline as the ligand. The scope of the reaction is broad tolerating a range of electron-releasing or electron-withdrawing substituents on the nitroarene, and the ortho-substituent can be modified to diastereoselectively construct benzoxazines, dihydrobenzothiazines, tetrahydroquinolines, tetrahydroquinoxalines, or tetrahydrobenzooxazepines. Mechanistic investigations indicated that the reaction proceeds via a nitrosoarene intermediate, and kinetic analysis of the reaction revealed a first order rate dependence in catalyst- and nitroarene concentration, and an inverse kinetic order in acetate was observed. The difference in rates between PhSiH3 and PhSiD3 was found to be 1.50 ± 0.09, and investigation of the temperature dependence of the reaction rate revealed that the activation parameters to be ΔH‡ = 13.5 kcal•mol–1 and ΔS‡ = –39.1 cal•mol–1•K–1. These data were interpreted to indicate that the turnover-limiting step to be hydride transfer from iron to the coordinated nitroarene, which occurs through an ordered transition state with little Fe–H bond breaking.

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Section: Fe-catalyzed Indole Synthesismentioning

confidence: 98%