Reaction of Organocopper Reagent

Breakthrough was brought by using an ephedrine-derived chiral aminoalcohol 8 to effect conjugate addition of organolithiums with over 90% enantioselectivity (Eq. (12.14)) [37]. The relationships between cluster structure and enantiofacial selection are a matter of discussion [38]. The sense of the observed enantiofacial selection was rationalized by the model 9. 

Conjugate addition of methyllithium with cyclic alkenone was mediated by aminoalcohol 10 having a bomane skeleton, and afforded the corresponding methyl adduct in excellently high ee (Eq. (12.15)) [39]. Although the reaction needs a stoichiometric amount of chiral alcohol, a batch process was applicable to mimic the catalytic process. 

The first epoch-making catalytic process was developed by using a chiral copper amide derived from an amine 16 in 1990. With 3 mol% of aminotroponeimine (16) and copper, butylmagnesium chloride reacted with cyclohexenone to afford the corre.sponding adduct in 74% ee (Eq. (12.20)) [45]. 

Chirally modified thiocuprates are used mostly in the catalytic process. The success is probably due to the high affinity of the sulfur atom to copper and the great stability of the sulfur-copper bond. 

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Scheme 8.1. Nucleophilic Substitution Reactions of Organocopper Reagents...

Enantioselective Reactions of Organocopper Reagents. Several methods have been developed for achieving enantioselectivity with organocopper reagents. Chiral auxiliaries can be used for example, oxazolidinone auxiliaries have been utilized in conjugate additions. The outcome of these reactions can be predicted on the basis of steric control of reactant approach, as for other applications of the oxazolidinone auxiliaries. 

High stereoselectivity was also observed in the reaction of organocopper reagents 215 with the aldehyde moiety of (774-diene)Fe(CO)3 complexes 214 (Scheme 98).491... 

Subsequently, Corey and coworkers40 42 described nucleophilic addition reactions of organocopper reagents and organocuprates to several acceptor-substituted dienes. The... 

The reaction of organocopper reagents with simple, unactivated acetylenes, an example of the last class of methods in the preceding list, serves as the basis of the procedure described here. This addition reaction... 

G. H. Posner, Conjugate Addition Reactions of Organocopper Reagents, in W. G. Dauben, Ed., Organic Reactions, Vol. 19, Chap. 1, John Wiley Sons, New York, 1972 M. J. Chapdelaine and M. Hulce, Tandem Vicinal Difunctionalization 0-Addition to a,/3-Unsaturated Carbonyl Substrates Followed by cx-Functionalization, in L. A. Paquette, ed., Organic Reactions, Vol. 38, Chap. 

Review Taylor has reviewed the conjugate addition-enolate trapping reactions of organocopper reagents, in particular of lithium dialkylcuprates (131 references). 

G. H. Posner, Conjugate Addition Reactions of Organocopper Reagents," Organic Reactions 19, 1 (1972). 

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... 

Table 2. Reaction of Organocopper Reagents with Allylic Mesylates...

Cot gate addition. Conjugate addition reactions of organocopper reagents have been reviewed by Posner. ... 

The reaction of organocopper reagents with acid chlorides affords the corresponding ketones in high yields.Retrosynthetically, the reaction amounts to an alkylation of a carboxylic acid. 

Reaction of Organocopper Reagents Prepared from Organozinc Reagents with Externai Chirai Ligands... 

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