The direct alkylation of pyridines has emerged as an expedient and atom-economical strategy for the preparation of alkylated pyridines which form the core structures of many biologically active compounds, pharmaceuticals, and agrochemicals. Consequently, a range of metal-mediated or radical-mediated C-H alkylation reactions of pyridines have been successfully developed in the presence of transition-metal-catalysts. However, concerns regarding high costs and the presence of residual metal impurities often make these approaches unsuitable for industrial and pharmaceutical applications. In this poster, I will describe an unprecedented base-promoted deborylative alkylation of Heterocyclic N-oxides using 1,1-diboryl-alkanes as alkylsources. The reaction proceeds efficiently for a wide range of heterocyclic N-oxides and 1,1-diborylalkanes with excellent regioselectivity. The utility of the developed method is demonstrated by the sequential C-H arylation and methylation of heterocyclic N-oxides. The reaction also can be applied for the direct introduction of a methyl group to 9-O-methylquinine N-oxide, thus it can serve as a powerful method for late-stage functionalization.

Transition-metal-free regioselective alkylation of heterocyclic N-oxides using 1,1-diborylalkanes as alkylating reagents

253rd National Meeting (2017)

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