Enolate anions from organolithium reagents

Organocuprates are generated from an organolithium reagent (see Chapter 15, Section 15.5) and a cuprous salt such as Cul (cuprous iodide). When two equivalents of n.-butyllithium are mixed with Cul in ether at -10°C, the product is lithium dibutylcuprate, 52. When 52 reacts with a conjugated ketone such as methyl vinyl ketone (10), the product is enolate anion 53, which gives 54... 

Because the reactions of related in -cyclohexadienyl complexes are synthetically valuable, the reactions of this ligand have been studied extensively. An outline of how this chemistry can be conducted on the Fe(CO)j fragment is shown in Equation 11.51. A variety of cyclohexadienes are readily available from Birch reduction of substituted aromatics. Coordination and abstraction of a hydride, typically by trityl cation, leads to cationic cyclohexadienyl complexes. These cyclohexadienyl complexes are reactive toward organolithium, -copper, -cadmium, and -zinc reagents, ketone enolates, nitroal-kyl anions, amines, phthalimide, and even nucleophilic aromatic compounds such as indole and trimethoxybenzene. Attack occurs exclusively from the face opposite the metal, and exclusively at a terminal position of the dienyl system. This combination of hydride abstraction and nucleophilic addition has been repeated to generate cyclohexa-diene complexes containing two cis vicinal substituents. The free cyclohexadiene is ttien released from the metal by oxidation with amine oxides. ... 

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