Organocopper compound arylation

The relative reactivity of organocopper compounds in additions to 6 and 7 is as follows vinyl > aryl > isopropyl > ethyl > methyl. 

Organocopper compounds have been trapped by coordination with organic bases. In addition, arylcopper compounds (ArCu) have been independently prepared and shown to give biaryls (ArAr ) when treated with aryl iodides (Ar I). A similar reaction has been used for ring closure. 

Reactions with hthium or Grignard reagent yield alkyl or aryl copper(I) derivatives, respectively. Such organocopper compounds containing Cu-Cu bonds are formed only by Cu+ and not Cu2+ ions. 

The most important substrates for substitutions of this type are alkenyl and aryl triflates, bromides, or iodides (Sections 16.1-16.4). The most important organometallic compounds to be introduced into the substrates contain Cu, Mg, B, Zn or Sn. The metal-bound C atom can be sp2-, sp2-, or. sp-hybridized in these compounds, and each of these species, in principle, is capable of reacting with unsaturated substrates. Organocopper compounds often (Section 16.1, 16.2), but not always substitute without the need for a catalyst (Section 16.4.5). Grignard compounds substitute in the presence of catalytic amounts of Ni complexes (Section 16.3), while organoboron (Section 16.4.2), organozinc (Section 16.4.3) and organotin (Section 16.4.4) compounds are typically reacted in the presence of Pd complexes (usually Pd(PPhj)4). 

Arylation and Alkyny lalion of Neutral Organocopper Compounds I... 

Arylations, Alkenylations and Alkynylations of Neutral Organocopper Compounds II... 

Few comparisons have been made among the relative stabilities of other classes of organocopper compounds. Generally, for simple derivatives, the order of decreasing stability is RC=CCu > Aryl-Cu > Alkyl-Cu. For vinylcopper compounds, 2-butenylcopper is more stable than propenylcopper 294). The higher homologs of methylcopper and lithium dimethylcuprate are less stable (69, 276, 297). 

The thermal decomposition of aryl- and vinylcopper compounds is an alternative method of obtaining dimeric products from organocopper compounds. Both methods have been used extensively by Kauffmann and co-workers 153-164). Thermal decomposition of organocopper compounds of the type ZN=C(R)—CHRCu affords suitable precursors for a variety of 1,4-diketones. Thermal decomposition is not applicable to all organocopper compounds (see Section III,B,3). Various oxidations and dimerizations are listed in Table V. 

There is presumably more than a subtle difference between the reactions of alkyl and aryl halides with organocopper compounds, as a straightforward nucleophilic displacement of aryl halide by the d electrons of a copper species is hardly likely. Simple aryl halides are nearly all inert to the usual nucleophiles, such as alkoxides, unless strongly activated by electron-attracting groups in the ortho and para positions. However, coordination of the halogen to copper may be sufficient to... 

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