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Title: Nitrene Insertion into Aromatic and Benzylic C−H Bonds Catalyzed by Copper Complexes of Fluorinated Bis‐ and Tris(pyrazolyl)borates

Journal Article · · ChemCatChem
 [1];  [2];  [2]; ORCiD logo [1]
  1. Department of Chemistry and Biochemistry The University of Texas at Arlington Arlington, Texas 76019 USA
  2. Department of Chemistry Center for Advanced Scientific Computing and Modeling (CASCaM) University of North Texas Denton, Texas 76203 USA

Abstract Fluorinated bis‐ and tris(pyrazolyl)boratocopper complexes catalyze the nitrene insertion to C−H bonds of aromatic hydrocarbons efficiently producing amination products in good to excellent yields at room temperature. Imidoiodanes, PhI=NTs (Ts= p ‐toluenesulfonyl) and PhI=NNs (Ns= p ‐nitrophenylsulfonyl) serve as the nitrene source. The bis(pyrazolyl)borate catalyst [H 2 B(3,5‐(CF 3 ) 2 Pz) 2 ]Cu(NCMe) with PhI=NNs produced the arene C−H functionalized product of mesitylene in 87 % yield with only trace amounts of benzylic C−H insertion. The use of [H 2 B(3,5‐(CF 3 ) 2 ‐4‐(NO 2 )Pz) 2 ]Cu(NCMe) that has an even weakly donating pyrazolate generated the arene C−H insertion product exclusively. The tris(pyrazolyl)borate complex [HB(3,5‐(CF 3 ) 2 Pz) 3 ]Cu(NCMe), in contrast, generated the benzylic amination product from mesitylene and PhI=NNs in 82 % yield with only very minor amounts of arene C−H functionalization. DFT calculations suggest that Cu‐nitrene moiety generated from [HB(3,5‐(CF 3 ) 2 Pz) 3 ]Cu(NCMe) and PhI=NNs activates the benzylic C−H bond of mesitylene via a hydrogen atom abstraction (HAA) followed by a radical rebound (RR) pathway, whereas the functionalization of sp 2 C−H bonds of mesitylene by [H 2 B(3,5‐(CF 3 ) 2 Pz) 2 ]Cu(NNs) ensues possibly via a nitrene addition to the arene core.

Sponsoring Organization:
USDOE
OSTI ID:
1562578
Journal Information:
ChemCatChem, Journal Name: ChemCatChem Journal Issue: 19 Vol. 11; ISSN 1867-3880
Publisher:
Wiley Blackwell (John Wiley & Sons)Copyright Statement
Country of Publication:
Germany
Language:
English

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