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Synfacts 2008(3): 0304-0304
DOI: 10.1055/s-2008-1042738
DOI: 10.1055/s-2008-1042738
Metal-Mediated Synthesis
© Georg Thieme Verlag Stuttgart · New YorkMixed Lithium-Zinc Species for the Deprotonation of Five-Membered Aromatic Heterocycles
Contributor(s):Paul Knochel, Tobias ThalerJ.-M. L’Helgoual’ch, A. Seggio, F. Chevallier, M. Yonehara, E. Jeanneau, M. Uchiyama*, F. Mongin*
Université de Rennes 1 and Université Claude Bernard Lyon 1, Villeurbanne, France; RIKEN, Wako-shi, Japan
Deprotonative Metalation of Five-Membered Aromatic Heterocycles Using Mixed Lithium-Zinc Species
J. Org. Chem. 2008, 73: 177-183
Université de Rennes 1 and Université Claude Bernard Lyon 1, Villeurbanne, France; RIKEN, Wako-shi, Japan
Deprotonative Metalation of Five-Membered Aromatic Heterocycles Using Mixed Lithium-Zinc Species
J. Org. Chem. 2008, 73: 177-183
Further Information
Publication History
Publication Date:
21 February 2008 (online)
Key words
deprotonation - five-membered aromatic heterocycles - zincation
Significance
The article describes a novel synergetic approach towards the chemoselective deprotonation of five-membered heterocycles. Hereby, (TMP)2Zn (0.5 equiv) and LiTMP (0.5 equiv) are prepared in situ from LiTMP and ZnCl2 .TMEDA which are employed in a 3:1 ratio.
Comment
This novel base system allows the deprotonation of sensitive heteroarenes, such as benzoxazoles, which are prone to ring opening when treated with a neat lithium base. The mechanistic proposal given in this article is supported by NMR data and DFT calculations.