Métallation et fonctionnalisation sélectives des (pyridyl)pipérazines en solution et en phase supportée

Abstract : The aim of this work is the fonctionnalization of pyridine derivatives bearing several heteroatoms on the substituent. Pyridylpiperazines were choosen as substrates and lithiated using the n-BuLi-LiDMAE superbase. We carried out the metallation of N-protected pyridylpiperazines very efficiently regardless of the protective group. An iterative functionalisation was also carried out under the same conditions on isomers 3 and 4. The lithiation awas also studied on solid phase. Several observations could be made from the metalations: an excess of superbase was necessary, and the metalation temperatures varied from 25 to -78°C with respect to the isomer. The functional derivatives were easily deprotected into amines or carbamates. The additional contribution of a heteroatom in bis-(pyridyl)piperazines did not modify the quantity of superbase. The mono bis-fonctionnalisation could be controlled by temperature. We also varied the nature of complexing heteroatoms on the pyridine substituent. When the substituent was placed in position 4, a notable decrease of the superbase amount was necessary for metallation achievement. These same substituents located in position 2, required the ususal excess of lithiating reagent.
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Frédéric Louërat. Métallation et fonctionnalisation sélectives des (pyridyl)pipérazines en solution et en phase supportée. Autre. Université Henri Poincaré - Nancy 1, 2007. Français. ⟨NNT : 2007NAN10123⟩. ⟨tel-01748247⟩

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