Lithium divinylcuprate

The following example shows lithium divinylcuprate serving as a Michael donor, adding to the double bond of an a,/3-unsaturatcd ketone. In this conjugate addition, the vinyl group adds to the (3 carbon atom to give an enolate ion. Protonation at the a carbon gives the product. 

Addition of an acyl anion or its equivalmt to a,p-unsaturated ketones is an important synthetic mediod for 1,4-dicaibonyl compounds. In the palladium method for 1,4-dicartxHiyl compounds, a vinyl Grignard or vinyllithium reagent is used as a synthetic equivalent of the acetyl anion. Reaction of lithium divinylcuprate with 2-cyclohexenone (44) afforded 3-vinylcyclohexanone (45). which was oxidized to the 1,4-diketone (46 Scheme 12). ° ... 

What organic halide is needed to convert lithium divinylcuprate [(CH2=CH)2CuLfl to each compound ... 

Patterson and Fried found that the clean lithium enolate (14), generated by conjugate addition of the lithium divinylcuprate (15) to cyclopentenone with subsequent trapping of the initial enolate with TMS-Cl and cleavage of the TMS enol ether with lithium amide in liquid ammonia-THF, could be alkylated in a reasonable yield with the (Z)-allylic iodide (16) to give the 11-deoxyprostaglandin derivative (17 ... 

Conjugate addition of lithium divinylcuprate to enones gives a,)9-unsatura-ted ketones (Hooz and Layton, 1970). Addition of di-cw- or di-tran -propenyl-cuprate to 2-cyclohexenone proceeds in a completely stereospecific manner with retention of double-bond geometry (Casey and Boggs, 1971). Particularly important is the application to the synthesis of a variety of prostaglandin... 

When vinylcopper or allylcopper compounds are allowed to react with a, -acetylenic esters, 1,3- and 1,4-dienes are synthesized stereospecifically (Naf and Degan, 1971 Corey et al., 1972). The reaction of CCLVI and lithium divinylcuprate gives the addition product (CCLVII) in a purely cis form in >90% yield. The latter is converted readily to the prostaglandin intermediate (CCLVIII). Vinylcopper may be a superior reagent for this purpose. 

What alkyl halide would be needed to react with lithium divinylcuprate [(CH2=CH)2CuLi] for the synthesis of each of the following compounds ... 

Lithium divinylcuprate prepared from cuprous iodide and vinyl-lithium has been used for introduction of cis angular vinyl substituents, (384)... 

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