- Photoactive electron donor-acceptor complex platform for Ni-mediated C(sp3)-C(sp2) bond formation
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A dual photochemical/nickel-mediated decarboxylative strategy for the assembly of C(sp3)-C(sp2) linkages is disclosed. Under light irradiation at 390 nm, commercially available and inexpensive Hantzsch ester (HE) functions as a potent organic photoreductant to deliver catalytically active Ni(0) species through single-electron transfer (SET) manifolds. As part of its dual role, the Hantzsch ester effects a decarboxylative-based radical generation through electron donor-acceptor (EDA) complex activation. This homogeneous, net-reductive platform bypasses the need for exogenous photocatalysts, stoichiometric metal reductants, and additives. Under this cross-electrophile paradigm, the coupling of diverse C(sp3)-centered radical architectures (including primary, secondary, stabilized benzylic, α-oxy, and α-amino systems) with (hetero)aryl bromides has been accomplished. The protocol proceeds under mild reaction conditions in the presence of sensitive functional groups and pharmaceutically relevant cores.
- Kammer, Lisa Marie,Badir, Shorouk O.,Hu, Ren-Ming,Molander, Gary A.
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p. 5450 - 5457
(2021/05/05)
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- Combined Cyanoborylation, C-H Activation Strategy for Styrene Functionalization
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A one-pot multicomponent copper-catalyzed protocol for borylation/ortho-cyanation of styrene derivatives followed by a Suzuki-Miyaura coupling provides a platform to explore the factors that control the selectivity between distal or proximal functionalization of arenes. The development of divergent nitrile-directed C-H functionalization (acetoxylation, pivalation, and methoxylation) offers an effective approach to rapidly increase synthetic complexity. Finally, the development of a mild reductive decyanation allows a traceless method to access functionalized biaryl motifs.
- Ansel, Annabel Q.,Montgomery, John
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supporting information
p. 8538 - 8543
(2020/11/12)
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- Manganese-Catalyzed ortho-C?H Alkenylation of Aromatic N?H Imidates with Alkynes: Versatile Access to Mono-Alkenylated Aromatic Nitriles
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So far, the direct C?H alkenylation of aromatic nitriles with alkynes has not been achieved. Herein, we discribe the first manganese-catalyzed C?H alkenylation of aromatic N?H imidates to access mono-alkenylated aromatic nitriles. The reaction is accelerated by the presence of a catalytic amount of sodium pivalate. This protocol is also highlighted by the simple catalytic system, good compatibility of functional groups, and excellent mono-/dialkenylation selectivity as well as E/Z stereoselectivity. (Figure presented.).
- Yang, Xiaoxu,Jin, Xiqing,Wang, Congyang
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supporting information
p. 2436 - 2442
(2016/08/16)
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- Palladium-phosphinous acid-catalyzed cross-coupling of aryl and acyl halides with aryl-, alkyl-, and vinylzinc reagents
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(Chemical Equation Presented) Several palladium-phosphinous acids have been prepared and employed in cross-coupling reactions of aryl or acyl halides with aliphatic and aromatic organozinc reagents. The POPd7-catalyzed reaction of aryl halides, including electron-rich aryl chlorides, and arylzinc reagents was found to afford biaryls exhibiting alkoxy, alkylthio, amino, ketone, cyano, nitro, ester, and heteroaryl groups in 75-93% yield. Excellent results were obtained with sterically hindered substrates which gave di- and tri-ortho-substituted biaryls in up to 92% yield. Aryl halides also undergo POPd7-catalyzed aryl-vinyl and aryl-alkyl bond formation under mild conditions. Styrenes and alkylarenes were prepared in 79-93% yield from aryl halides and vinyl or alkylzinc reagents. The replacement of aryl halides by acyl halides provides access to ketones which were produced in up to 98% yield when POPd was used as catalyst. This approach overcomes the limited substrate scope, reduced regiocontrol, and low functional group tolerance of traditional Friedel-Crafts acylation methods.
- Xu, Hanhui,Ekoue-Kovi, Kekeli,Wolf, Christian
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p. 7638 - 7650
(2008/12/22)
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- Radical cyclisation onto nitriles
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Iminyl radicals, generated by 5-exo cyclisation of alkyl, vinyl and aryl C-centred radicals onto nitriles, undergo β-scission (nitrile translocation), reduction or tandem cyclisation onto alkenes depending on the nature of the α-substituent. 5-exo Cyclisations of aryl radicals onto nitriles undergo nitrile translocation when the α-substituent is CN, CO2R, SO2Ph or CONMe2. The rate of translocation is faster than 5- or 6-exo cyclisation onto alkenes or 1,5-hydrogen abstraction of allylic hydrogens. When the α-substituents are alkyl, the intermediate iminyl radicals do not undergo nitrile translocation. (C) 2000 Elsevier Science Ltd.
- Bowman,Bridge,Brookes
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p. 8989 - 8994
(2007/10/03)
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- Inhibition of Fc epsilon RI-mediated activation of mast cells by 2,3,4-trihydropyrimidino[2,1-a]isoquinolines.
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Assays based on reporter gene technology represent today an important tool in the pharmaceutical industry for discovering novel compound classes interfering with the activation and signaling of target cells after stimulation. Here we describe a reporter g
- Scholz,Schmidt,Prieschl,Csonga,Scheirer,Weber,Lembachner,Seidl,Werner,Mayer,Baumruker
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p. 1050 - 1059
(2007/10/03)
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- ADDITION OF ARYL RADICALS GENERATED FROM ELECTROCHEMICAL REDUCTION OF ARYL HALIDES ON CARBON-CARBON DOUBLE BONDS.
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Aryl radicals generated by electrochemical reduction of aryl halides in aprotic medium react with styrene and its derivatives to give arylated addition compounds.
- Chami, Zoubida,Gareil, Monique,Pinson, Jean,Saveant, Jean-Michel,Thiebault, Andre
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p. 639 - 642
(2007/10/02)
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