Deprotometalation of Substituted Pyridines and Regioselectivity-Computed CH Acidity Relationships - Université de Rennes Access content directly
Journal Articles Tetrahedron Year : 2016

Deprotometalation of Substituted Pyridines and Regioselectivity-Computed CH Acidity Relationships

Abstract

A series of methoxy- and fluoro-pyridines have been deprotometalated in tetrahydrofuran at room temperature by using a mixed lithium-zinc combination obtained from ZnCl2·TMEDA (TMEDA = N,N,N’,N’-tetramethylethylenediamine) and LiTMP (TMP = 2,2,6,6-tetramethylpiperidino) in a 1:3 ratio, and the metalated species intercepted by iodine. Efficient functionalization at the 3 position was observed from 4-methoxy, 2-methoxy, 2,6-dimethoxy, 2-fluoro and 2,6-difluoropyridine, and at the 4 position from 3-methoxy and 2,3-dimethoxypyridine. Interestingly, clean dideprotonation was noted from 3-fluoropyridine (at C2 and C4) and 2,6-difluoropyridine (at C3 and C5). The obtained regioselectivities have been discussed in light of the CH acidities of the substrates, determined both in the gas phase (DFT B3LYP and G3MP2B3 levels) and in THF solution. In the case of methoxypyridines, the pKa values have also been calculated for complexes with LiCl and LiTMP
Fichier principal
Vignette du fichier
Deprotometalation of Substituted Pyridines-accepted.pdf (331.61 Ko) Télécharger le fichier
mmc1.pdf (1.14 Mo) Télécharger le fichier
Origin : Files produced by the author(s)
Origin : Files produced by the author(s)

Dates and versions

hal-01290443 , version 1 (27-04-2016)

Identifiers

Cite

Madani Hedidi, Ghenia Bentabed-Ababsa, Aicha Derdour, Yury S. Halauko, Oleg A. Ivashkevich, et al.. Deprotometalation of Substituted Pyridines and Regioselectivity-Computed CH Acidity Relationships. Tetrahedron, 2016, 72 (17), pp.2196-2205. ⟨10.1016/j.tet.2016.03.022⟩. ⟨hal-01290443⟩
105 View
224 Download

Altmetric

Share

Gmail Facebook X LinkedIn More