Search results for "Lithium Compounds"
showing 4 items of 24 documents
Trap Spectroscopy by the Glow Rate Technique using Bleaching of Colour Centres
2002
An application of the glow rate technique (GRT) for analysis of the parameters of thermostimulated decay of colour centres is presented using the data on the decay of radiation defects in LiBaF 3 :Fe crystals created by X rays at 300 K. The GRT offers a procedure for evaluation of the mean activation energy as a function of temperature in the case of arbitrary thermostimulated relaxation kinetics represented by the trap distribution function. The experimental procedure involves at least two subsequent measurements of thermostimulated decay kinetics at different heating rates. It is shown that the decay of the F type centres is governed by interaction of mobile anion vacancies with F A and F…
tBuLi-Mediated One-Pot Direct Highly Selective Cross-Coupling of Two Distinct Aryl Bromides.
2015
A Pd-catalyzed direct cross-coupling of two distinct aryl bromides mediated by tBuLi is described. The use of [Pd-PEPPSI-IPr] or [Pd-PEPPSI-IPent] as catalyst allows for the efficient one-pot synthesis of unsymmetrical biaryls at room temperature. The key for this selective cross-coupling is the use of an ortho-substituted bromide that undergoes lithium-halogen exchange preferentially.
Stereoselective Conjugate Addition of Mixed Organoaluminum Reagents to ?,?-Unsaturated N-Acyloxazolidinones Derived from Carbohydrates.
2005
The stereoselective synthesis of β-branched carboxylic acid derivatives was accomplished by conjugate addition of mixed organoaluminum reagents to chiral α,β-unsaturated N-acyloxazolidinones. Mixed organoaluminum reagentswere generated in situ by transmetalation of Grignard or organolithium compounds with methylaluminum dichloride. Efficient stereocontrol was achieved using different bicyclic glycosamine-derived oxazolidinones, yielding alternatively (R)- or (S)-configured β-branched carboxylic acid derivatives.
ChemInform Abstract: A Simple and Efficient Route to 1,4-Diketones from Squaric Acid.
2010
Abstract Squaric acid derivatives react with organolithium compounds at room temperature to afford with excellent yields after hydrolysis, symmetrical and unsymmetrically substituted oxygenated 1,4 diketones bearing alkyl, aryl or heteroaryl groups at the carbonyl positions. In the case of aromatic or heteroaromatic ketones the enol tautomers are also obtained.