Co‐Condensation Reactions of Substituted Aromatic Compounds with Lithium Atoms at 77 K

Lithium atoms were co‐condensed with +I‐substituted benzene derivatives like trimethyl(phenyl)silane and tert ‐butylbenzene in the presence of THF at 77 K, which resulted in C−H bond activation, to produce the aryllithium compound as well as the coupling of the substituted phenyl radicals. Other +I‐substituted benzene derivatives like xylene and mesitylene failed to react with lithium atoms in the presence of THF. Oxygen and nitrogen donor substituted benzene derivatives (anisole, N , N ‐dimethylaniline, and N , N ‐dimethylbenzylamine) showed activation of the ortho C−H bond when co‐condensed with lithium atoms in the presence of THF. However, when thioanisole was co‐condensed with lithium atoms and THF, a C−S bond cleavage occurred instead. These results were interpreted with the aid of DFT calculations, which show π‐ and σ‐complexes between the lithium clusters and benzene derivatives as reactive intermediates. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)