Journal of the American Chemical Society 2004-11-17

Formation of benzynes from 2,6-dihaloaryllithiums: mechanistic basis of the regioselectivity.

Antonio Ramírez, John Candler, Crystal G Bashore, Michael C Wirtz, Jotham W Coe, David B Collum

Index: J. Am. Chem. Soc. 126(45) , 14700-1, (2004)

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Abstract

The key elimination step for the formation of 3-chloro- and 3-fluorobenzyne from 2-chloro-6-fluorophenyllithium displays a pronounced solvent-dependent regioselectivity. 6Li and 13C NMR spectroscopic studies on 2-chloro-6-fluorophenyllithium reveal a single monomeric aryllithium, suggested by DFT computational studies to be a trisolvate. Rate studies indicate that the elimination of LiCl and LiF proceeds via trisolvated and disolvated monomers, respectively.