1003-19-6Relevant articles and documents
Configuration and 13C NMR Spectra of Alkylcyclopropane Derivatives
Touillaux, R.,Meerssche, M. Van,Dereppe, J. M.,Leroy, G.,Weiler, J.,Wilante, C.
, p. 71 - 72 (1981)
Eight alkylcyclopropane derivatives were prepared in a conventional manner and analysed by 13C NMR spectroscopy.Additivity parameters were calculated from the chemical shifts of the endocyclic carbons, and the configurational structures derived for these compounds are confirmed by the internal coherence found for this set of parameters.
Reactions of tert-Butyllithium with α,ω-Dihaloalkanes. Evidence for Single-Electron-Transfer-Mediated Metal-Halogen Interchange Involving Alkyl Radical-Halide Ion Adducts
Bailey, William F.,Gagnier, Paul R.,Patricia, Jeffrey J.
, p. 2098 - 2107 (2007/10/02)
The reactions of tert-butyllithium (t-BuLi) with primary α-iodo-ω-haloalkanes and α,ω-dibromoalkanes have been investigated in experiments conducted at -23 deg C in n-pentane-diethyl ether (3:2 by volume) solution.It has been found that production of an α-lithio-ω-haloalkane (1) by metal-halogen interchange at one end of a 1,3-, 1,4-, or 1,5-dihalide results in intramolecular coupling to give cycloalkanes in high yield.As the chain length of the dihalide is increased beyond five carbon atoms the production of an α,ω-dilithio species by interchange at bothends of the dihalide ceases to be excluded by cyclization of 1 and a precipitous drop in the yield of cycloalkane was found to occur in reactions of 1,6-diiodoalkanes with t-BuLi.Metal-halogen interchange was the exclusive process observed in reactions of α,ω-dihalides with t-BuLi provided at least one halogen of the substrate was an iodine.By contrast, similar treatment of α,ω-dibromoalkane provided only minor amounts of product attributable to metal-halogen interchange.Under conditions that provide an essentially quantitative yield of carboxylic product from reductive cyclization of 1 generated from 1,5-diiodo-3,3-dimethylpentane, the corresponding 1,5-dibromide was converted to a mixture composed of cycloalkane, products from Wurtz-type coupling with t-BuLi, and quantities of parent alkane from formal reduction of the dihalide.The mechanism of the metal-halogen interchange was further probed by using 6-halo-1-hexene substrates.Observation of cyclized product from the reaction of t-BuLi with 6-bromo- and 6-iodo-1-hexene demonstrated that the interchange between t-BuLi and primary alkyl bromides and iodides occurs predominantly via single-electron-tranfer (SET) process.Incorporation of alkyl radical-halide ion adducts with halogen dependent lifetimes as intermediates following SET from alkyllithium to alkyl halide serves to explain the disparate behavior of alkyl bromides and iodides when treated with t-BuLi.A unifield SET-mediated mechanism for metal-halogen interchange and Wurtz coupling is presented.