Organozinc compounds, and

Lack of cooling during preparation of the Simmons-Smith organozinc reagent caused the reaction to erupt. The possibly pyrophoric nature of organozinc compounds and the presence of ether presents a severe fire hazard [1]. An alternative, safer method of activating the zinc for the reaction involves use of ultrasonic irradiation rather than the copper-zinc couple [2]. 

Most semi-conducting zinc compounds, such as the chalcogenides ZnS and ZnSe, are made from simple organozinc compounds and volatile sources of chalcogens, such as H2S and H2Se. Because of the enormous economic importance of these solid-state materials, these MOCVD processes are among the major consumers of organozinc compounds. 

Because of the separation of this chapter into fundamental synthetic and structural aspects of organozinc compounds and the applications of these compounds in organic synthesis, many topics are treated twice, but with decidedly different emphases. By way of example, the important organozinc alkoxides are covered first in the inorganometallic section, where the emphasis is on their syntheses, structures, and applications other than in organic synthesis. Later, in Section 2.06.16.2, the uses of such compounds as chiral catalysts in asymmetric addition reactions are discussed. 

Because of the enormous volume of information regarding the use of organozinc derivatives in organic chemistry, this survey is focused only on recent major trends in this area. Valuable information about preparation methods of major types of organozinc compounds and their reactions can be found in two recent books246 247 and reviews. There have been a number of reviews devoted to specific applications of organozinc reagents... 

In addition, the organozinc compound obtained from ethyl 4-bromobutanoate reacts under similar conditions to those described previously, with 4-bromoacetophenone, to give the corresponding product in good yield15. The preparation of organozinc compounds and their cross-coupling with aryl halides can be carried out in one step (equation 7). 

The electrochemical preparation of organozinc compounds obtained from the corresponding aromatic halides and with the use of a nickel complex as catalyst is only efficient in dimethylformamide as solvent. Moreover, in most cases and as described previously, the reaction requires the presence of excess 2,2 -bipyridine (five molar equivalents with respect to nickel) to achieve the transmetallation reaction leading to the organozinc compound and to avoid the formation of biaryl, Ar-Ar (equation 53). 

This is also in agreement with the fact that a transmetallation reaction leading to the organozinc compound and the regeneration of Co2+ occurs (equation 63). 

The zincates K [ZnR(tBuNCH=CHN Bu)] contain the diazabutadiene fragment. They have been made, via a series of radical-anion complexes, from the alkylation of B uN = CHCH = N Bu by potassium in the presence of organozinc compounds, and characterized as THF and Et20 adducts, 70 and 71, respectively. Each forms linear coordination polymers comprising alternate potassium cations and zincate anions held together... 

These few examples demonstrate the broad range of the synthetic potential of organozinc compounds and provide a foretaste of what can be achieved with these highly effective and synthetically valuable reagents. 

The past decade has seen extensive development of cross-coupling reactions of organozinc compounds and organic halides catalyzed by nickel or palladium catalysts. Although nickel-based catalysts are more reactive with respect to the organic halide partner, the number of failures with these catalysts and the greater selectivity realized with palladium-based catalysts have resulted in the almost exclusive use of the latter group of catalysts for these reactions. 

Organomercury compounds are widely used for syntheses of organometallic compounds by the transmetalation or metathesis reaction similar to organozinc compounds. For example, organozinc compounds and organomagnesium compounds (1866) are prepared by the transmetalation of organomercury compounds with a metal [30,31]. 

Organozinc compounds and organoboron compounds are also prepared with organoaluminum compounds as shown in eqs. (7.28) and (7.29) [15]. 

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