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Enantioselektive Protonierung von γ‐Butyrolacton‐Enolaten
Author(s) -
Gerlach Uwe,
Haubenreich Thomas,
Hünig Siegfried,
Klaunzer Norman
Publication year - 1994
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.19941271023
Subject(s) - chemistry , protonation , carbanion , deprotonation , lithium (medication) , medicinal chemistry , deuterium , enantioselective synthesis , stereoselectivity , proton , stereochemistry , organic chemistry , catalysis , ion , medicine , physics , quantum mechanics , endocrinology
Stereoselective Protonation of Carbanions, 6 [1] . — Enantioselective Protonation of γ‐Butyrolactone Enolates * The lithium enolates 3 Li – 7 Li , produced from 3–7 by LDA or LiHMDS in THF, are protonated with eleven chiral proton sources at ‐78°C in THF which produced high enantioselectivities with 1 Li and 2 Li [5] . Although the enolates ( 3 Li , 6 Li , 7 Li ) are not deuterated quantitatively [1] , 1 H‐ and 13 C‐NMR spectra in THF at ‐78°C reveal not only quantitative deprotonation ( 3 Li , 6 Li ) but also aggregation (dimerisation) and hindered rotation of the phenyl group in 3 Li . From comparison of the enantioselectivities produced by five chiral proton sources with 1 Li – 6 Li (Tab. 4) definite structure/selectivity correlations can not be derived both for the enolates and the proton sources.