Beilstein J. Org. Chem.2012,8, 50–60, doi:10.3762/bjoc.8.5
10.3762/bjoc.8.5 Abstract N,N-Diisopropyl-2-propylbenzamide 6-H undergoes lateral deprotonation by t-BuLi in the presence of the Lewis base PMDTA (N,N,N′,N″,N″-pentamethyldiethylenetriamine) to give a benzyllithium 6-Lil·PMDTA that incorporates a trigonal planar secondarycarbanion. In the solid state
observation of two structure-types for the carbanion in solution is explained theoretically and by NMR spectroscopy in terms of cis and trans isomerism imparted by partial double bond character in the arene–(α-C) bond.
Keywords: directed metallation; Lewis base; ligand effects; lithium; secondarycarbanion
crystallographic data for 6-Lil·L relative to that achievable for 3-Lil·PMDTA reveals significant structural parameters that are not available from the previously characterised secondarycarbanion [23].
Results and Discussion
Solid-state structural studies
Based on our knowledge of the ability of Lewis base
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Graphical Abstract
Scheme 1:
Molecular structures of 1/2-H and their corresponding ortho-lithiates [21].