- Oligomerization of 1-butene with a homogeneous catalyst system based on allylic nickel complexes
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The oligomerization of 1-butene with a nickel-based catalyst system constitutes an elegant synthesis method for obtaining linear octenes from readily available chemicals. It is well known that the bis-(cyclooctadiene)nickel(0)-complex (Ni(COD)2) can be used in combination with 1,1,1,5,5,5-hexafluoroacetylacetone (hfacac) forming [Ni-1] as a catalyst for the dimerization of 1-butene, which produces a linear octene yield of 75-83% at reaction temperatures between 70-80 °C. We are the first to demonstrate that it is also possible to use allylic nickel complexes in combination with hfacac to produce linear octenes with a selectivity of 70% under very mild reaction conditions and at low catalyst concentrations. Additionally the catalyst can be formed simply by adding the activator hfacac to a solution of the allylic nickel complex. No complicated synthesis or purification is needed.
- Behr,Bayrak,Peitz,Stochniol,Maschmeyer
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p. 41372 - 41376
(2015/05/27)
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- Enantioselective synthesis of tertiary and quaternary stereogenic centers: Copper/phosphoramidite-catalyzed allylic alkylation with organolithium reagents
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An efficient and highly enantioselective copper-catalyzed allylic alkylation of disubstituted allyl halides with primary and secondary organolithium reagents using phosphoramidite ligands is reported. The use of trisubstituted allyl bromides allows, for the first time, the enantioselective synthesis of all-carbon quaternary stereogenic centers with these reactive organometallic reagents.
- Fananas-Mastral, Martin,Perez, Manuel,Bos, Pieter H.,Rudolph, Alena,Harutyunyan, Syuzanna R.,Feringa, Ben L.
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supporting information; experimental part
p. 1922 - 1925
(2012/04/17)
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- Cyclization of methyl-substituted 6-heptenyl radicals
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(Matrix presented) The behavior of a series of methyl-substituted 6-heptenyl radicals, generated from the corresponding iodides ((Me3Si)3SiH, AIBN in benzene at 80°C), has been investigated. The stereoselectivity of the 6-exo cyclizations, affording dimethylcyclohexanes, is low, and sizable quantities of methylcycloheptane, generated via 7-endo cyclization, are also produced.
- Bailey, William F.,Longstaff, Sarah C.
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p. 2217 - 2219
(2007/10/03)
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