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Conformational Mobility and Preferences of Allyl‐Type Organometallic Intermediates: Dodec‐2‐enylpotassium
Author(s) -
Franzini Livia,
Moret Etienne,
Schlosser Manfred
Publication year - 1997
Publication title -
chemische berichte
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 0009-2940
DOI - 10.1002/cber.19971300113
Subject(s) - chemistry , metalation , isomerization , allylic rearrangement , butyllithium , reagent , conformational isomerism , catalysis , stereochemistry , medicinal chemistry , solvent , organic chemistry , molecule
Alk‐2‐enylpotassium compounds having the endo conformation are synthetically very valuable precursors of (Z)‐olefinic derivatives substituted at the outward allylic position. They may be generated by „stereoconservative’ metalation of the readily available (Z)‐alk‐2‐enes by using the superbasic mixture of butyllithium and potassium tert ‐butoxide or by metalation under similar conditions of stereorandom mixtures of alk‐2‐enes or alk‐1‐enes followed by torsional isomerization of the concomitantly formed exo conformers to the thermodynamically more stable endo species. The principal factors that dictate the rate and the extent of the endo/exo equilibration are the substrate geometry, the solvent, the temperature, the reagent stoichiometry, and catalysis.