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Abstract
The pyridine heterocycle continues to play a vital role in the development of human medicines. More than 100 currently marketed drugs contain this privileged unit, which remains highly sought after synthetically. We report an efficient means to access di- and trisubstituted pyridines in an efficient and highly controlled manner using transient 3,4-pyridyne intermediates. Previous efforts to employ 3,4-pyridynes for the construction of substituted pyridines were hampered by a lack of regiocontrol or the inability to later manipulate an adjacent directing group. The strategy relies on the use of proximal halide or sulfamate substituents to perturb pyridyne distortion, which in turn governs regioselectivities in nucleophilic addition and cycloaddition reactions. After trapping of the pyridynes generated in situ, the neighbouring directing groups may be removed or exploited using versatile metal-catalysed cross-coupling reactions. This methodology now renders 3,4-pyridynes as useful synthetic building blocks for the creation of highly decorated derivatives of the medicinally privileged pyridine heterocycle. The in situ trapping of pyridynes is an efficient method for the generation of a variety of substituted pyridines but, until now, the method has been hampered by a lack of regiocontrol. Here, proximal halide and sulfamate substituents are shown to perturb pyridyne distortion and thus govern regioselectivities in pyridyne reactions. Cite this article
Goetz, A., Garg, N. Regioselective reactions of 3,4-pyridynes enabled by the aryne distortion model. Nature Chem 5, 54–60 (2013). https://doi.org/10.1038/nchem.1504 