The direct synthesis of fluoro-aromatic derivatives of metals and non-metals

A series of Ni(0) compounds supported by electronically similar N-heterocyclic carbene (NHC) ancillary ligands with a range of %V bur were used as catalysts for aryl C− H bond silylation, germylation, and stannylation. The NHC steric bulk strongly influenced the selectivity of C−H functionalization to give new carbon−heteroatom bonds versus alkene hydroarylation, despite little structural change in the resting state of the catalysts. Studies were performed by reacting C 6 F 5 H and H 2 CCHER 3 (ER 3 = SnBu 3 , GePh 3 , SiMe 3 ) using catalytic amounts of Ni(COD) 2 and NHC ligands IPr, IMes, IBn, and i Pr 2 Im. Catalytic C−H stannylation to give C 6 F 5 SnBu 3 was facile with all ligands. The catalytic C−H germylation reaction was more difficult than stannylation but was demonstrated using H 2 CCHGePh 3 to give C 6 F 5 GePh 3 for all but the largest NHC. The bulkiest NHC, IPr, gave a 96:4 ratio of the hydroarylation product C 6 F 5 CH 2 CH 2 GePh 3 versus C 6 F 5 GePh 3 . The C−H silylation reactions required the highest temperatures and gave selective silylation product C 6 F 5 SiMe 3 only for the smallest IBn and i Pr 2 Im NHC ligands. Using the larger IMes carbene resulted in a 66:34 mixture of silylation and hydroarylation products, and the largest NHC, IPr, gave exclusive conversion to the hydroarylation product, C 6 F 5 CH 2 CH 2 SiMe 3 . DFT calculations are provided that give insight into the mechanism and key reaction steps, such as the relative difficulty of the critical β-Sn, Ge, and Si elimination steps.

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“…The solution was heated at 90 °C for 18 h. (68% NMR yield). The 19 F { 1 H} NMR spectrum was in good agreement with previously reported data …”

Section: Synthesis Characterization and Reactionssupporting

confidence: 91%

Influence of N-Heterocyclic Carbene Steric Bulk on Selectivity in Nickel Catalyzed C–H Bond Silylation, Germylation, and Stannylation

et al. 2018

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“…The maximum yield of compound I was 60%, and of compound II 27% [20]. Also a substitution of iodine by chlorine or bromine was described occurring at heating iodopentafluorobenzene with C1 2 or Br 2 at 120-150°C [21].…”

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confidence: 97%

Organofluorine Sulfur-containing Compounds: V. Joint Pyrolysis with Chlorine or Bromine of Polyfluoroarenethioles, Polyfluorohetarenethioles, and Their Derivatives

et al. 2005

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“…To further optimize the synthesis of tetraarylstannanes, we investigated the reaction of iodobenzene ( 1n ) with elemental tin. The reaction of alkyl halides with tin and tin alloys is a classical approach for the synthesis of symmetrical organotin compounds of the type R 4 Sn. , However, there is only one report that describes the direct synthesis of a tetraarylstannane (i.e., Sn(C 6 F 5 ) 4 ) by the reaction of elemental tin with an iodobenzene at 260 °C . Considering the great interest in functionalized tetraarylstannanes, we further investigated the observation that the reaction of untreated tin power with iodobenzene 1a results in the formation of tetraarylstannane 3a .…”

Section: Resultsmentioning

confidence: 99%

The Ullmann Coupling Reaction: A New Approach to Tetraarylstannanes

2006

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Several iodobenzenes form tetraarylstannanes, in addition to other products, under reaction conditions typically employed for the Ullmann reaction, i.e., activated copper bronze (a copper−tin alloy) and 7 days at 230 °C. The isolated yields of the tetraarylstannanes were low to good (8−58%). Significantly higher yields (54−64%) of tetraphenylstannane were obtained by the direct reaction of iodobenzene with an excess of tin powder (iodobenzene:tin = 1:1 w/w) under the same conditions. Crystal structure analysis reveals that tetrakis(4-carbomethoxyphenyl)stannane crystallizes in a tetragonal space group and has 4̄ symmetry, which is the case for many symmetrical tetraarylstannanes. However, tetrakis(2,4-dichlorophenyl)stannane, tetrakis(3,4-dichlorophenyl)stannane, and tetrakis(2,4-dimethylphenyl)stannane do not crystallize in a tetragonal space group and do not have real 4̄ symmetry.

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The direct synthesis of fluoro-aromatic derivatives of metals and non-metals

Cited by 19 publications

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Influence of N-Heterocyclic Carbene Steric Bulk on Selectivity in Nickel Catalyzed C–H Bond Silylation, Germylation, and Stannylation

Influence of N-Heterocyclic Carbene Steric Bulk on Selectivity in Nickel Catalyzed C–H Bond Silylation, Germylation, and Stannylation

Organofluorine Sulfur-containing Compounds: V. Joint Pyrolysis with Chlorine or Bromine of Polyfluoroarenethioles, Polyfluorohetarenethioles, and Their Derivatives

The Ullmann Coupling Reaction: A New Approach to Tetraarylstannanes

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