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Updated: Mar 23, 2026

A Protocol for Safe Lithiation Reactions Using Organolithium Reagents
Published on: November 12, 2016
Lithium Enolates Derived from Pyroglutaminol: Aggregation, Solvation, and Atropisomerism
Michael J Houghton1, Naomi A Biok1, Christopher J Huck1
1Department of Chemistry and Chemical Biology Baker Laboratory, Cornell University Ithaca , New York 14853-1301, United States.
Abstract:
Lithium enolates derived from protected pyroglutaminols were characterized by using (6)Li, (13)C, and (19)F NMR spectroscopies in conjunction with the method of continuous variations. Mixtures of tetrasolvated dimers and tetrasolvated tetramers in different proportions depend on the steric demands of the hemiaminal protecting group, tetrahydrofuran concentration, and the presence or absence of an α-fluoro moiety. The high steric demands of the substituted bicyclo[3.3.0] ring system promote dimers to an unusual extent and allow solvents and atropisomers in cubic tetramers to be observed in the slow-exchange limit. Pyridine used as a (6)Li chemical shift reagent proved useful in assigning solvation numbers.
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