Alkenes Organocopper reagents

By Wittig and related reactions (3-Dimethylaminopropyl)-triphenylphosphorane, 119 Sodium amide, 278 Vinyl(triphenyl)phosphonium bromide, 343 (E)-Alkenes By elimination reactions Arylselenocarboxamides, 22 Dichlorobis(cyclopentadienyl)-titanium, 102 Hydrogen peroxide, 145 From three-membered heterocycles Tributyltinlithium-Trimethylalu-minum, 320 Trisubstituted alkenes Chloromethyldiphenylsilane, 74 Organocopper reagents, 207 Alkenes (Methods to form alkenes)... 

The conjugate addition of organocopper reagents to ot,(3-alkynic esters, ketones, aldehydes and acids is a useful method for the preparation of various tri- and tetra-substituted alkenes,87 although addition to aldehydes is less common.88 Use of a vinylcuprate results in the formation of a conjugated dienone, which further highlights the importance of this methodology (equation 43 ).87... 

Tetrasubstituted alkenes. A new route to alkenes of this type involves as the initial step reaetion of ketones with 1 to form the tertiary alcohols 2. These alcohols are not acetylated under conventional methods, but are acetylated in satisfactory yields by acetyl chloride in the presence of silver cyanide. Reaction of 3 with organocopper reagents gives tetrasubstituted alkenes as a mixture of (E)- and (Z)-isomers, 4 and 5. The stereoselectivity of this reaction depends on the relative size of R and R. When R is more bulky than R, 5 is formed predominately. Both products can be halodesilylated to vinyl iodides 6 or 7 or to vinyl bromides by BrCN-AlCU. 

Organocopper Addition (Alkene to -Functionalized Product). Tri-n-butylphosphine-stabilized organocopper reagents add in a conjugate fashion to trans-cnoaic derivatives of the 10-dicyclohexylsulfonamidoisobomeol auxiliary from the less hindered C(a)-s ( r-face with excellent selectivity (eq 2) (Table 1). This type of reaction has formed the basis of several natural product syntheses. ... 

An organocopper reagent capable of transferring methylene to olefinic double bonds has been generated from diiodomethane and copper powder in aromatic hydrocarbon solvents (equation 46) . The reactivity of this reagent toward alkenes is similar to that of... 

Otaka, A., Watanabe, H., Yukimasa, A., et al. (2001) New access to a-substituted (Z)-fluoro-alkene dipeptide isosteres utilizing organocopper reagents under reduction-oxidative alkylation (R-OA) conditions. Tetrahedron Lett., 42, 5443-5446. 

Organocopper reagents can be made d which is prepared by reduction of CuCN prepared from Cul PR3 (R=Bu, Phi is in bromoaryl epoxides to give dihydrobenzot Defunctionalization of heteroalkeme salts, l,2-bis(phenyltelluro)alkenes. and k an electron-deficient substituent, are sele chalcogenides is affected, and the ketene However, the alkenylcopper intermediates... 

Alkenes. Normant et al. have developed a method for a regiospecific synthesis of 1-alkenes by addition of organocopper reagents to 1-alkynes. The copper reagents are prepared by the reaction of a Grignard reagent with cuprous bromide in ether at -40. The 1-alkyne is then added to this solution to form a... 

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