Ketones reactions with organocopper compounds

The synthetic application of organocopper compounds received a major impetus from the study of the catalytic effect of copper salts on reactions of Grignard reagents with y.,(i-unsaturated ketones.1 Whereas Grignard reagents normally add to conjugated enones to give the 1,2-addition product, the presence of catalytic amounts of Cu(I) results in... 

Because of the toxicity of cadmium compounds two alternative methods for the preparation of ketones from carboxylic acid derivatives are worthy of attention. The first involves the reaction of organocopper reagents [formed from copper(i) iodide and an alkyllithium] with a carboxylic acid chloride.12 7a,b... 

Addition to ot, -acetylenic esters and ketones (3, 108 6, 163-164). The addition of organocopper reagents to conjugated acetylenic carbonyl compounds is usually not stereospeciflc, although cis-addition predominates. Japanese chemists have found that the stereoselectivity in the reaction with alkylcopper reagents is markedly enhanced by use of the complex RCu BRj. Thus the reaction of dimethyl acetylenedicarboxylate with n-butylcopper complexed with tri-n-butylboron (or triethylboron) results in exclusive formation of the cis-adduct. In the absence of a trialkylborane the cis- and adducts are formed in the-ratio 85 15. 

We have found that alkynylsilanes are smoothly converted into alkynylcopper compounds by treatment with CuCl in l,3-dimethyl-2-imidazohdinone (DMI) the copper reagents can be isolated in good yields [563]. This study was the first example of preparation and isolation of organocopper compounds by use of organosilicon reagents. The Si-Cu transmetalation is applicable to the synthesis of alkynyl ketones by Cu-catalyzed alkynylation of acid chlorides (Scheme 10.217). We have also shown that a Cu-mediated system is effective in the cross-coupling reaction between arylsilanes or heteroarylsilanes and aryl hahdes [564]. 

Organocopper compounds, RCu, though less reactive toward acid halides, couple to give the corresponding ketones as well. Reaction of alkynylcoppers with acyl halides produces acetylenic ketones in good yields (Normant and Bourgain, 1970). 

Finally, not all applications of Cul involve organocuprates or related reagents. For example, Corey used Cul to catalyze intramolecular diazoalkene cyclization reactions, and Yates used Cul to catalyze the Wolff rearrangement of diazo ketones. Flouse recommended CuL(SBu2)2 for the intermolecular cyclo-propanation of alkenes with a-diazo ketones. The intermediates are undoubtedly organocopper species of some kind, perhaps Cu-carbene complexes however, it should be noted that Cu and Cu are more commonly used as catalysts in conjunction with diazo compounds. ... 

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