Organometallic compounds organocopper

Selective 1,4-additions of organometallic compounds to o ,/Tun saturated ketones can also be achieved starting from organocopper and organozinc reagents. We will treat this in Section 10.6. 

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). 

In this chapter, we have already seen that C,C couplings may involve organocopper, -magnesium, -boron and -zinc compounds. But the number of suitable organometallic compounds is not exhausted. A commonly used metal for coupling purposes is tin and organotin compounds are extensively used in Stille coupling reactions. 

Conversion of pyrylium salts with organolithium and Grignard reagents to pyrans via reductive alkylation or arylation has been enriched by applications of organocopper and other organometallic compounds as well as by photochemical activation. Several new studies with anions of C-acids have been published as well. 

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