Organoborohydride-catalyzed Chichibabin-type C4-position alkylation of pyridines with alkenes assisted by organoboranes |
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Authors: | Ying Wang Runhan Li Wei Guan Yanfei Li Xiaohong Li Jianjun Yin Ge Zhang Qian Zhang Tao Xiong Qian Zhang |
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Institution: | Jilin Province Key Laboratory of Organic Functional Molecular Design & Synthesis, Department of Chemistry, Northeast Normal University, Changchun 130024 China.; Institute of Functional Material Chemistry, Department of Chemistry, Northeast Normal University, Changchun 130024 China ; State Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, 345 Lingling Lu, Shanghai 200032 China |
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Abstract: | The first NaBEt3H-catalyzed intermolecular Chichibabin-type alkylation of pyridine and its derivatives with alkenes as the latent nucleophiles is presented with the assistance of BEt3, and a series of branched C4-alkylation pyridines, even highly congested all-carbon quaternary center-containing triarylmethanes can be obtained in a regiospecific manner. Therefore, the conventional reliance on high cost and low availability transition metal catalysts, prior formation of N-activated pyridines, organometallic reagents, and extra oxidation operation for the construction of a C–C bond at the C4-position of the pyridines in previous methods are not required. The corresponding mechanism and the key roles of the organoborane were elaborated by the combination of H/D scrambling experiments, 11B NMR studies, intermediate trapping experiments and computational studies. This straightforward and mechanistically distinct organocatalytic technology not only opens a new door for the classical but still far less well-developed Chichibabin-type reaction, but also sets up a new platform for the development of novel C–C bond-forming methods.The first NaBEt3H-catalyzed intermolecular Chichibabin-type alkylation of pyridines with alkenes as the latent nucleophiles is presented in the presence of BEt3, and a series of branched C4-alkylated pyridines were obtained in a regiospecific manner. |
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