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Lithium Enolates Derived from Pyroglutaminol: Aggregation, Solvation, and Atropisomerism.

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 ?-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.

SUBMITTER: Houghton MJ

PROVIDER: S-EPMC5245164 | biostudies-literature | 2016 May

REPOSITORIES: biostudies-literature

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Lithium Enolates Derived from Pyroglutaminol: Aggregation, Solvation, and Atropisomerism.

Houghton Michael J MJ Biok Naomi A NA Huck Christopher J CJ Algera Russell F RF Keresztes Ivan I Wright Stephen W SW Collum David B DB

The Journal of organic chemistry 20160425 10

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 dimer ...[more]

PMID: 27035057

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