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Creators/Authors contains: "Mao, Jianyou"

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  1. Free, publicly-accessible full text available April 21, 2024
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  4. Enantioenriched azaarylmethyl amine derivatives are useful building blocks in synthetic and medicinal chemistry. To access these valuable motifs, an enantioselective palladium-catalyzed benzylation of azaarylmethyl amine pronucleophiles is introduced. Of note, this is a rare application of asymmetric (2-naphthyl)methylation of pro-nucleophiles with high p K a values (p K a ≈ 34 in DMSO). Control experiments support the notion that the coordination of Li + to the azaaryl nitrogen plays a critical role in the substitution process. With this procedure, enantioenriched (2-naphthyl)methylene azaarylmethyl amines with a variety of azaaryl groups (pyridyl, pyrazine, quinoxaline and isoquinoline) and cyclic and acyclic amines are readily obtained with good yields and enantioselectivities up to 99%.
  5. Azaindoles and azaindolines are important core structures in pharmaceuticals and natural products, which have found wide applications in the field of medicinal chemistry. In this study, we developed a novel one-pot method for selectively synthesizing 7-azaindoles and 7-azaindolines, which can be generated by reactions between the readily available 2-fluoro-3-methylpyridine and arylaldehydes. The chemoselectivity is counterion dependent, with LiN(SiMe 3 ) 2 generating 7-azaindolines and KN(SiMe 3 ) 2 furnishing 7-azaindoles. A range of substituents can be introduced under these conditions, providing handles for further elaboration and functionalization.
  6. Chemoselectivity is one of the most challenging issues facing the chemical sciences. In this study, the first highly chemoselective reactions of N -acylpyrroles via either an anionic Fries rearrangement (pyrrole dance) or a C–H functionalization of toluene to provide aryl benzyl ketones are advanced. This efficient and operationally simple approach enables the synthesis of either 2-aroylpyrroles or aryl benzyl ketones in good to excellent yields under transition metal-free conditions. The choice of base plays a crucial role in controlling the chemoselectivity. The aroylation of toluene derivatives was observed with N -acylpyrroles when subjected to KN(SiMe 3 ) 2 , while anionic Fries rearrangement products were produced with LiN(SiMe 3 ) 2 . Surprisingly, cross-over experiments indicate that the anionic Fries rearrangement is an intermolecular process. The aroylation reaction has the advantage over Weinreb amide chemistry in that it does not require preformed organometallic reagents or cryogenic temperatures.
  7. Abstract

    Nonsteroidal anti-inflammatory drug derivatives (NSAIDs) are an important class of medications. Here we show a visible-light-promoted photoredox/nickel catalyzed approach to construct enantioenriched NSAIDs via a three-component alkyl arylation of acrylates. This reductive cross-electrophile coupling avoids preformed organometallic reagents and replaces stoichiometric metal reductants by an organic reductant (Hantzsch ester). A broad range of functional groups are well-tolerated under mild conditions with high enantioselectivities (up to 93% ee) and good yields (up to 90%). A study of the reaction mechanism, as well as literature precedence, enabled a working reaction mechanism to be presented. Key steps include a reduction of the alkyl bromide to the radical, Giese addition of the alkyl radical to the acrylate and capture of the α-carbonyl radical by the enantioenriched nickel catalyst. Reductive elimination from the proposed Ni(III) intermediate generates the product and forms Ni(I).