Highly functionalized azines are important structural motifs of pharmaceuticals, pesticides, dyes, and advanced synthetic intermediates. The currently available methods of azine substitution are often non-regioselective. On the other hand, the use of azine N-oxides may allow for regioselective synthesis of substituted azines. Previously our research has delved into the regioselective synthesis of 2-subsituted azines through the use of azine N-oxides, potassium tert-butoxide, and perfluoroakylsilanes en route to 2-perfluoroalkyl-substituted azines. Inexpensive Grignard reagents and copper catalysts can also provide a host of 2-substituted azines from azine N-oxides. Currently our research is focused on exploring the potential of regioselective C-H activation of azine N-oxides through the use of the N-O bond acting as a directing group. Various electrophiles have been used as coupling partners with azine N-oxides under thermal and microwave conditions in good to high yields. After coupling further modifications provide a variety of highly functionalized azines. Dual C-H activation of azine N-oxides has also been achieved providing regiospecific dimeric structures, currently inaccessible through any means. Details of the mechanism have been elucidated by kinetic experiments and DFT computational studies.

Regioselective C-H activation of azine N-oxides in arylation and dimerization

249th National Meeting (2015)

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