On the deprotonation of 3,5-dichloropyridine using lithium bases: in situ infrared spectroscopic studies

Elodie Weymeels (1) , Hacan Awad (2) , Laurent Bischoff (3) , Florence Mongin (4) , Francois Trécourt (5) , Guy Quéguiner (5) , Francis Marsais (1)

1 IRCOF - Institut de Chimie Organique Fine
2 LU - Lebanese University [Beirut]
3 COBRA - Chimie Organique et Bioorganique : Réactivité et Analyse
4 ISCR - Institut des Sciences Chimiques de Rennes
5 UNIROUEN - Université de Rouen Normandie

Deprotonation of 3,5-dichloropyridine using LTMP and BuLi was monitored in real time by infrared spectroscopy. It appeared that the substrate was rapidly deprotonated. Transient structures between the substrate and the lithio derivative were detected. The absorbances recorded for the lithio derivative showed that the structures obtained using LTMP and BuLi were similar. When BuLi was used to deprotonate, a complete deuteration of the lithio derivative was noted upon quenching with D 2 O. The latter did not allow the quantification of the lithio derivative when LTMP was used, since only partial deuteration was observed.

Keywords: Metallation; Pyridines; In situ IR; Mechanism; Deuteration

Domains: Chemical Sciences; Chemical Sciences; Organic chemistry; Chemical Sciences; Medicinal Chemistry; Chemical Sciences; Radiochemistry; Chemical Sciences; Material chemistry; Chemical Sciences; Inorganic chemistry; Chemical Sciences; Catalysis

Elodie Weymeels, Hacan Awad, Laurent Bischoff, Florence Mongin, Francois Trécourt, et al.. On the deprotonation of 3,5-dichloropyridine using lithium bases: in situ infrared spectroscopic studies. Tetrahedron, 2005, 61 (13), pp.3245-3249. ⟨10.1016/j.tet.2004.10.098⟩. ⟨hal-02385058⟩