Iron(II) catalyzed reductive radical cyclization reactions of bromoacetals in the presence of NaBH4: optimization studies and mechanistic insights

TETRAHEDRON

卷:72

Article

Kyne, Sara H.^1,3  Leveque, Christophe¹  Zheng, Shiwen¹  Fensterbank, Louis¹  Jutand, Anny²  Ollivier, Cyril¹ 

[1] UPMC Univ Paris 06, Sorbonne Univ, UMR CNRS 8232, Inst Parisien Chim Mol,CC 229, 4 Pl Jussieu, F-75005 Paris, France

[2] UPMC Univ Paris 06, Sorbonne Univ, PSL Res Univ, CNRS UMR PASTEUR 8640,Ecole Normale Super,Dept Ch, 24 Rue Lhomond, F-75231 Paris 05, France

[3] Lincoln Univ, Sch Chem, Joseph Banks Labs, Lincoln LN6 7DL, England

关键词: Iron;    Radical cyclization;    Homogenous catalysis;    Reduction;    Electrochemistry;    NMR spectroscopy;   

DOI  :  10.1016/j.tet.2016.08.039

来源: Elsevier

【 摘 要 】

5-Exo-trig radical reductive cyclization reactions of bromoacetals are catalyzed by iron in the presence of the reducing agent NaBH4. Both iron(II) and iron(III) were found to effectively mediate these reactions. As shown by cyclic voltammetry, iron(III) can be reduced to an iron(II) precatalyst before passing through an identical reaction mechanism in which monoelectronic activation of the substrate would occur by an anionic hydridoiron(I) complex. Further studies have established that both the substrate (iodo- vs bromo-derivative) and the precatalytic mixture are decisive in determining the reaction outcome. (C) 2016 Elsevier Ltd. All rights reserved.

【 授权许可】

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