132576-42-2Relevant academic research and scientific papers
Configurational Stability of Chiral Organolithium Comopunds on the Time Scale of their Addition to Aldehydes
Hoffmann, Reinhard W.,Julius, Manfred,Chemla, Fabrice,Ruhland, Thomas,Frenzen, Gerlinde
, p. 6049 - 6060 (1994)
A test based on kinetic resolution has been applied to the α-bromo-, α-phenylseleno- and α-phenylthio-alkyllithium compounds 1, which shows that addition of these species to the chiral aldehyde 6 occurs faster than enantiomer equilibrium of the organolithium compounds. - Keywords: Configurational Stability; Organolithium Compounds
Chiral organometallic reagents. Part XVII. Formation of diastereoisomeric complexes between α-phenylselanylalkyllithium compounds and chiral diamines
Hoffmann, Reinhard W.,Klute, Wolfgang,Dress, Ruprecht K.,Wenzel, Andreas
, p. 1721 - 1726 (2007/10/02)
The racemic α-phenylselanylalkyllithium compound 6 is monomeric in diethyl ether and forms diastereoisomeric complexes with a variety of chiral diamines.Diastereoisomer ratios were determined from 77Se NMR spectroscopy to lie around 60:40 for most examples, but reached 90:10 with N,N,N',N'tetramethylcyclopentane-1,2-diamine (22).The complexation constants for the formation of the diastereoisomeric complexes 24a and 24b formed from 6 with the latter ligand were estimated by NMR titration to be > 800 dm3 mol-1 and > 90 dm3 mol-1.The diastereoisomeric complexes 24 epimerize at the lithium bearing stereocentre with a barrier of ΔG(excit.) = 12.1 +/-0.3 kcal mol-1 at -4 deg C.As this epimerization process is not slower than the racemization of the uncomplexed alkyllithium compound 6, the complexes 24 equilibrate directly and do not have to dissociate into 6 in order to equilibrate.
