Chelated aryllithium reagents: ring size and chelating group effects

Org Lett. 2001 Jan 11;3(1):33-6. doi: 10.1021/ol0067080.

Abstract

[figure: see text] Chelation and aggregation in phenyllithium reagents with potential 5-, 6-, and 7-ring chelating ether and amine ortho substituents have been examined utilizing variable-temperature 6Li and 13C NMR spectroscopy, 6Li and 15N isotope labeling, and the effects of solvent additives. Both ether and amine form strong 5-ring chelates; 6-ring ether chelates compete well with THF, but 6-ring amine chelates barely do, and 7-ring amine chelates do not. o-Methoxymethylphenyllithium (4) forms an open dimer (9) and a pentacoordinate monomer with PMDTA (10).