The Donor-Base-Free Aggregation of Lithium Diisopropyl Amide in Hydrocarbons Revealed by a DOSY Method

Angew Chem Int Ed Engl. 2015 Jun 8;54(24):6994-8. doi: 10.1002/anie.201502576. Epub 2015 May 27.

Abstract

Lithium diisopropyl amide (LDA) is a very prominent reagent that plays a key role in organic synthesis, serving as a base par excellence for a broad range of deprotonation reactions. However, the state of aggregation in solution in the absence of donor bases was unclear. In this paper we solved this problem by employing DOSY NMR experiments based on a newly elaborated external calibration curve (ECC) approach with normalized diffusion coefficients.

Keywords: NMR spectroscopy; aggregation; lithium amides; reactive intermediates.