Structural and synthetic insights into pyridine homocouplings mediated by a β-diketiminato magnesium amide complex

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Hevia, Eva and McLellan, Ross and Davin, Laia and Clegg, William and Kennedy, Alan and Probert, Michael R (2018) Structural and synthetic insights into pyridine homocouplings mediated by a β-diketiminato magnesium amide complex. Chemistry - A European Journal. ISSN 1521-3765 (https://doi.org/10.1002/chem.201803297)

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Abstract

Reaction of [(DippNacnac)Mg(TMP)] (1) with 4‐subtituted pyridines proceeds via sequential regioselective metalation and 1,2‐addition to furnish a range of symmetric 4,4'R2‐2,2'‐bipyridines in good yield, representing a new entry into bipyridine synthesis. Interestingly, the reaction with of 1 with 2‐OMe‐pyridine led to formation of asymmetric bipyridine 6, resulting from the C6‐magnesiation of the heterocycle followed by a C‐C coupling step by addition to the C2 position of a second, non‐metallated molecule, and subsequent elimination of [DippNacnacMgOMe]2 (7). Synthesis combined with spectroscopic and structural analysis help rationalise the underlying processes resulting in the observed reactivity, and elucidates the key role of the sterically encumbered β‐diketiminate ligand plays in determining regioselectivity.

ORCID iDs

Hevia, Eva ORCID logoORCID: https://orcid.org/0000-0002-3998-7506, McLellan, Ross ORCID logoORCID: https://orcid.org/0000-0001-9700-0258, Davin, Laia, Clegg, William, Kennedy, Alan ORCID logoORCID: https://orcid.org/0000-0003-3652-6015 and Probert, Michael R;
CORE (COnnecting REpositories)