104293-08-5Relevant academic research and scientific papers
Effect of solvent and temperature on the lithium?bromine exchange of vinyl bromides: Reactions of n -butyllithium and t -butyllithium with (E)-5-bromo-5-decene
Bailey, William F.,Luderer, Mark R.,Uccello, Daniel P.,Bartelson, Ashley L.
experimental part, p. 2661 - 2666 (2010/08/19)
The outcome of reactions of (E)-5-bromo-5-decene (1), a representative vinyl bromide, with t-BuLi or n-BuLi at 0 °C and room temperature, respectively, in a variety of solvent systems has been investigated. Vinyl bromide 1 does not react with t-BuLi in pure heptane; however, the presence of even small quantities of an ether in a predominantly heptane medium resulted in virtually complete consumption of 1 at 0 °C, resulting in nearly the same distribution of products, including 60?80% of (Z)-5-decenyllithium, regardless of the solvent composition. Vinyl bromide 1 reacts slowly with n-BuLi at room temperature in a variety of ether and heptane-ether mixtures to afford a mixture of products including significant quantities of recovered starting material. The results of these experiments demonstrate that lithium?bromine exchange between a vinyl bromide and either t-BuLi or n-BuLi at temperatures significantly above ?78 °C is not an efficient method for the generation of a vinyllithium.
Silafunctional Compounds in Organic Synthesis. 32. Stereoselective Halogenolysis of Alkenylsilanes: Stereochemical Dependence on the Coordination State of the Leaving Silyl Groups
Tamao, Kohei,Akita, Munetaka,Maeda, Kimio,Kumada, Makoto
, p. 1100 - 1106 (2007/10/02)
Halogenation of (E)-1-octenyltrimethylsilane (1), -trifluorosilane (2), and -pentafluorosilicate(2-) (3) by iodine chloride, bromine, and N-bromosuccinimide has been examined in nonpolar solvents, mostly carbon tetrachloride, and in polar solvents, mostly dimethylformamide, in the dark.Cleavage reactions of 1 proceed uniformly with inversion of configuration to form (Z)-1-octenyl halides, while 3 is cleaved with retention of configuration to form (E)-1-octenyl halides.A dual selectivity is observed with 2: inversion in nonpolar solvents and retention in polar solvents.Further spectral and mechanistic studies on 2 have provided a general rule for correlation between the stereochemical courses of the halogen cleavage reactions and the coordination states of the silicon center at the stage of attacking by electrophiles.Thus, while attack on ordinary tetracoordinate silicon compounds (trans addition) followed by nucleophilic attack on silicon (anti elimination) leads to inversion, attack on extracoordinate silicon species immediately followed by cleavage of the activated silicon-carbon bond results in retention of the olefin geometry.On the basis of the new aspect, one-pot synthesis of (E)- and (Z)-alkenyl bromides from acetylene has been achieved in combination with hydrosilation by triethoxysilane.
