Stoichiometric reactions copper reagents

The stoichiometric reaction of organolithium or Grignard reagents with copper halides allows direct formation of organocopper species(103). 

Cu(0) species. Alternatively, the Cu(n) species may first undergo oxidation by an external oxidant (or internal redox process) to a Cu(m) intermediate, and then undergo reductive elimination to provide the product and a Cu(i) species. Re-oxidation to Cu(n) would then, in theory, complete the catalytic cycle, but in practice, most reactions of this type have been performed with stoichiometric amounts of the copper reagent. 

Singhal et al. [78, 79] have described a titrimetric method for the determination of low levels of Oxamyl residues in soils. Their investigations revealed that after hydrolysis Oxamyl gave a brown precipitate with carbon disulphide and an alkaline solution of copper(II) sulphate. This reaction suggested a procedure for the determination of Oxamyl by titration with ethylene diamine tetracetic acid of the copper remaining unreacted to the 1-(2 pyridylazo)-2-naphthol end-point indicator). The following stoichiometric reaction appeared to occur between Oxamyl and the reagents ... 

Application of the manganese and copper catalysed electrochemical reaction between acetic anhydride and styrenes is as efficient as the process using stoichiometric amounts of reagent [27], The reaction between acetic anhydride and buta-... 

Cul-catalyzed reactions of RLi and RMgX. Cul-catalyzed reactions of these reagents with unsaturated substrates, carbonyl compounds, and epoxides reported since 1970 have been reviewed (89 references). Where possible, use of stoichiometric and catalytic copper reagents was compared. 

Reports by the groups of Chan, Evans, and Lam in 1998 revealed an alternative method to conduct copper-mediated couplings that form C(aryl)-0 and C(aryl)-N bonds. In this process, arylboronic acids react with compounds containing N-H or 0-H bonds in the presence of a Cu(II) reagent or catalyst. TTiese reactions were initially conducted with stoichiometric amounts of copper reagents. " Amines, anilines, amides, ureas, carbamates, and sulfonamides underwent N-arylation in moderate to excellent yields by this process (Equation 19.124). The commercial availability of boronic acids and the ability to conduct these arylations in air under mild conditions has caused this method to be adopted quickly for synthetic applications on a small scale. 

Efficient and selective coupling of aryl and vinyl halides with N, O, and C nucleophiles are indispensable and important transformations to construct useful compounds. Over 110 years ago, Ullmann and Goldberg found the synthesis of aryl ethers and aryl amines by C-N and C-O bond-forming reactions in the presence of copper powder or copper salt. However, even until the late twenty century, these transformations often required stoichiometric amounts of copper reagent in polar solvents (such as N-methylpyrrolidone, nitrobenzene, and dimethylformamide) at high reaction temperatures (>200 °C). These harsh reaction conditions frequently led to... 

It may be apparent that reactions of MA and derivatives with organometallics, either in stoichiometric or catalytic amounts, have a potential of yielding a multiplicity of products, but in some cases selectivities can be controlled to make them potentially useful. The homogeneous catalytic approach involving Pd or copper reagents appears quite promising. 

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