The reactions of ketone dilithio α,β-dianions with imines and hydrazones were investigated. The nucleophilic addition reaction to C–N double bonds took place selectively at the β-position of dianions to form lithium Z-enolates containing a lithium amide portion, which is then transformed into γ-amino ketones and related compounds by the subsequent reaction with electrophiles.
The cross-coupling reaction of dianion cuprates, generated from ketone α,β-dianions and copper salts, with acid chlorides, was studied. The reaction gave good to moderate yields of unsymmetrical 1,4-diketones. The consecutive treatment of a dianion cuprate with cyclohexanecarbonyl chloride and methyl iodide or two different acid chlorides gave 2-methyl-substituted 1,4-diketone or triketone, respectively
An Anionic Strategy for Three- and Four-Component Coupling Reactions Leading to Ketone Frameworks Based on Vinylogous Conversion of Dilithio Ketone α,β-Dianions
[reaction: see text] Ketonealpha,delta-dianions are generated by vinylogous extension of ketonealpha,beta-dianions with alkenes such as vinylarenes, vinylsilanes, and vinyl sulfides, which then undergo reactions at the delta and alpha positions with different electrophiles, creating ketone frameworks. This work represents a cascade-type anion method that achieved three- and four-carbon component
Ketone dilithio alpha,beta- and alpha,beta'-dianions can be generated by a tin-lithium exchange reaction of the lithium enolate of beta-tributyltin substituted ketones. A chelation-aided approach, which employs beta-dichlorobutyltin substituted ketones and n-BuLi, is also useful for the generation of ketone alpha,beta-dianions having the Z-geometry at the alkene. The generated dianions can be transformed into substituted ketones by reaction with various carbon electrophiles. (c) 2005 Elsevier Ltd. All rights reserved.