A Stereospecific Synthesis of Trisubstituted Alkenes via Hydridation of Dialkylhaloboranes Followed by Hydroboration-Iodination of Internal Alkynes
Dialkylvinylboranes, prepared conveniently via the hydridation of dialkylhaloboranes in the presence of an internal alkyne, react with iodine under basic conditions to produce trisubstituted alkenes of established stereochemistry, providing a general synthesis of trisubstituted alkenes with unambiguous stereochemistry.
Brown, Herbert C.,Basavaiah, D.,Kulkarni, Surendra U.
PROCESS FOR THE PRODUCTION OF A WELL FLUIDS BASE OIL VIA METATHESIS OF ALPHA-OLEFINS
Disclosed is a process for preparation of compositions having utility as well fluid base oils. The process involves metathesis of alpha-olefins followed by isomerization of the metathesis products. The base oils resulting from the process of this invention are environmentally friendly in that they are only mildly toxic to marine life, are highly biodegradable and have very low pour point temperatures. These properties make the base oils ideal candidates for use as components of well fluids for cold climates and offshore applications.
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Page 26
(2008/06/13)
Organic synthesis with sulphones no. XXXIV. Uncatalysed addition versus nickel catalysed coupling reaction of vinylic sulfones with Grignard reagents. A stereoselective synthesis of olefins and dienes
Grignard reagents undergo Michael addition to vinylic sulfones.With a β-β-disubstituted vinylic sulfone an unexpected dimer is obtained.Under nickel catalysis methyl, aryl and alkenyl Grignard reagents displace the sulfonyl group of the readily available α,β-unsaturated sulfones.Methyl, resp. phenyl substituted olefins or conjugated dienes are formed.Under appropriate conditions the reaction proceeds with complete retention of configuration.
Fabre, Jean-Luc,Julia, Marc,Verpeaux, Jean-Noel
p. 762 - 771
(2007/10/02)
BIOMIMETIC METHYL TRANSFER TO OLEFINS
Conditions have been found under which trisubstituted olefins can be methylated with diaryl methyl sulfonium salts in 2,6-di-t-butylpyridine.The pattern of methylated compounds formed is similar to that of the enzymatic methylation of Δ24 steroids side chains with S-adenosylmethionine as a methyl donor.
Julia, M.,Marazano, C.
p. 3717 - 3724
(2007/10/02)
Organic synthesis with sulfones no. XXXV. Iron catalysed condensation and hydrogenolysis of vinylic sulfones with Grignard reagents. A stereoselective synthesis of di- and trisubstituted olefins
Vinylic sulfones are readily available in the E or Z configuration.Condensation with primary Grignard reagents occurs stereospecifically in the presence of iron catalysts, leading to trisubstituted olefins.With secondary Grignards stereospecific hydrogenolysis to 1,2-disubstituted olefins is observed.
Fabre, Jean-Luc,Julia, Marc,Verpeaux, Jean-Noel
p. 772 - 778
(2007/10/02)
Couplage mixte entre sulfones vinyliques et reactifs de Grignard en presence de sels de metal de transition: synthese stereoselective d'olefines trisubstituees.
A new cross coupling reaction of vinylic sulphones with Grignard reagents catalyzed by nickel and iron complexes is described.This reaction is stereospecific : trisubstituted olefins of defined stereochemistry are obtained in good yield.
Fabre, Jean-Luc,Julia, Marc,Verpeaux, Jean-Noel
p. 2469 - 2472
(2007/10/02)
General Stereospecific Synthesis of Trisubstituted Alkenes via Stepwise Hydroboration
Iodination of alkenylalkylbromoboranes, obtained via the hydroboration of internal alkynes with alkylbromoboranes, in the presence of sodium methoxide in methanol, results in the formation of trisubstituted alkenes of established stereochemistry, thus providing a general synthesis of trisubstituted alkenes with unambiguous stereochemistry.
Brown, Herbert C.,Basavaiah, D.
p. 5407 - 5409
(2007/10/02)
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