- Palladium-Catalyzed Suzuki–Miyaura Cross-Coupling of Secondary α-(Trifluoromethyl)benzyl Tosylates
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A palladium-catalyzed C(sp3)?C(sp2) Suzuki–Miyaura cross-coupling of aryl boronic acids and α-(trifluoromethyl)benzyl tosylates is reported. A readily available, air-stable palladium catalyst was employed to access a wide range of functionalized 1,1-diaryl-2,2,2-trifluoroethanes. Enantioenriched α-(trifluoromethyl)benzyl tosylates were found to undergo cross-coupling to give the corresponding enantioenriched cross-coupled products with an overall inversion in configuration. The crucial role of the CF3 group in promoting this transformation is demonstrated by comparison with non-fluorinated derivatives.
- Brambilla, Marta,Tredwell, Matthew
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supporting information
p. 11981 - 11985
(2017/09/20)
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- Intramolecular Reactivity of Arylcarbenes: Derivatives of o-Tolylcarbene
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Various CH2X groups have been attached to the ortho position of phenylcarbene.If 2'- or 3'-C-H bonds are present, as in 23 (X = Me), 71 (X = CMe3), and 58 (X = SiMe3), C-H insertion leading to five- or six-membered rings predominates in the gas phase and competes with intermolecular reactions in solution.The formation of benzocyclobutenes via insertion into 1'-C-H bonds is a very minor reaction path of 23 and 71.In contrast, 58 produces substantial amounts of the benzocyclobutene 59 by way of C-Si insertion, particularly in the gas phase.Insertion into the Si-Me bonds of 58 also occurs while the C-F bonds of 37 (X = CF3) and 50 (X = F) are inert.In the gas phase, 37 and 50 give mainly benzocyclobutenes whereas intermolecular reactions prevail in solution.The effects of sensitization and of solvent polarity suggest that benzocyclobutenes arise from singlet arylcarbenes.The amount of carbene-carbene rearrangement decreases in the order 7 (X = H) > 37 (X = CF3) > 23 (X = Me); no rearrangement was observed with 50 (X = F), 58 (X = SiMe3), and 71 (X = CMe3).
- Kirmse, Wolfgang,Konrad, Wolfgang,Schnitzler, Dirk
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p. 3821 - 3829
(2007/10/02)
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