Lithium diisopropylamide solvated by hexamethylphosphoramide: substrate-dependent mechanisms for dehydrobrominations.

doi:10.1021/JA060964B

Paper

Lithium diisopropylamide solvated by hexamethylphosphoramide: substrate-dependent mechanisms for dehydrobrominations.

Published Nov 11, 2006 · Yun Ma, Antonio Ramirez, K. Singh

Journal of the American Chemical Society

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23

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Abstract

Lithium diisopropylamide-mediated dehydrobrominations of exo-2-bromonorbornane, 1-bromocyclooctene, and cis-4-bromo-tert-butylcyclohexane were studied in THF solutions and THF solutions with added hexamethylphosphoramide (HMPA). Rate studies reveal a diverse array of mechanisms based on mono-, di-, and trisolvated monomers as well as triple ions. The results are contrasted with analogous eliminations in THF in the absence of HMPA.

Study Snapshot

Lithium diisopropylamide-mediated dehydrobrominations of exo-2-bromonorbornane, 1-bromocyclooctene, and cis-4-bromo-tert-butylcyclohexane in THF solutions with he

PopulationOlder adults (50-71 years)

Sample size24

MethodsObservational

OutcomesBody Mass Index projections

ResultsSocial networks mitigate obesity in older groups.

Paper

Lithium diisopropylamide solvated by hexamethylphosphoramide: substrate-dependent mechanisms for dehydrobrominations.

References

Citations

Construction of stereogenic center beta to the N-Pyrrolidinyl moiety via diastereoselective reactions of tricyclic lactones and the synthesis of (−)-Indolizidine 195G

Diastereoselective reactions of tricyclic lactones can create new stereogenic centers and enable the total synthesis of ()-indolizidine 195G.

Photoinduced Palladium-Catalyzed Regio- and Chemoselective Elimination of Primary Alkyl Bromides: A Mild Route to Synthesize Unactivated Terminal Olefins.

This efficient method for photoinduced regio- and chemoselective elimination of alkyl halides yields unactivated terminal olefins for organic synthesis, preserving secondary and tertiary alkyl bromides.

Merging Halogen-Atom Transfer (XAT) and Cobalt Catalysis to Override E2-Selectivity in the Elimination of Alkyl Halides: A Mild Route toward contra-Thermodynamic Olefins.

This study presents a novel strategy for removing alkyl halides, enabling access to contra-thermodynamic olefins through the interplay of halogen-atom transfer and cobalt catalysis.

Sodium Diisopropylamide-Mediated Dehydrohalogenations: Influence of Primary- and Secondary-Shell Solvation

Sodium diisopropylamide-mediated dehydrohalogenations are facile and complementary to lithium diisopropylamide in THF, with primary-shell solvation effects dominating secondary-shell effects.

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