19398-88-0Relevant articles and documents
Catalytic, oxidant-free, direct olefination of alcohols using Wittig reagents
Khaskin,Milstein
supporting information, p. 9002 - 9005 (2015/05/27)
Reported here is the catalytic, acceptorless coupling of alcohols with in situ generated, non-stabilized phosphonium ylides to form olefins as major products. The reaction uses low catalyst loadings and does not require added oxidants. Hydrogenation of the product is minimized and the reaction leads to Z (aliphatic) or E (benzylic) stereospecificity.
Selective semihydrogenation of alkynes on shape-controlled palladium nanocrystals
Chung, Jooyoung,Kim, Chanhoi,Jeong, Hansaem,Yu, Taekyung,Binh, Do Huy,Jang, Jyongsik,Lee, Jaichan,Kim, B. Moon,Lim, Byungkwon
, p. 919 - 925 (2013/08/25)
A systematic study on the selective semihydrogenation of alkynes to alkenes on shape-controlled palladium (Pd) nanocrystals was performed. Pd nanocrystals with a cubic shape and thus exposed {100} facets were synthesized in an aqueous solution through the reduction of Na2PdCl4 with L-ascorbic acid in the presence of bromide ions. The Pd nanocubes were tested as catalysts for the semihydrogenation of various alkynes such as 5-decyne, 2-butyne-1,4-diol, and phenylacetylene. For all substrates, the Pd nanocubes exhibited higher alkene selectivity (>90 %) than a commercial Pd/C catalyst (75-90 %), which was attributed to a large adsorption energy of the carbon-carbon triple bond on the {100} facets of the Pd nanocubes. Our approach based on the shape control of Pd nanocrystals offers a simple and effective route to the development of a highly selective catalyst for alkyne semihydrogenation. Catalysis3: The semihydrogenation of various alkynes by Pd nanocubes was investigated. The nanocubes exhibited high alkene selectivity and complete cis-selectivity, thus surpassing the Lindlar catalyst. The shape control of Pd nanocrystals provides a simple and efficient way for generating highly selective catalysts for the semihydrogenation of alkynes.
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.