From organomercurials

Another major incident concerning methyl mercury was the severe pollution of Minamata bay in Japan (see Box 8.1). Here fish, fish-eating and scavenging birds, and humans feeding upon fish all died from organomercury poisoning. There may have been localized declines of marine species in this area due to methyl mercury, but there is no clear evidence of this. 

Entry 5 is an example of the use of fra-(trimethylsilyl)silane as the chain carrier. Entries 6 to 11 show additions of radicals from organomercury reagents to substituted alkenes. In general, the stereochemistry of these reactions is determined by reactant conformation and steric approach control. In Entry 9, for example, addition is from the exo face of the norbornyl ring. Entry 12 is an example of addition of an acyl radical from a selenide. These reactions are subject to competition from decarbonylation, but the relatively slow decarbonylation of aroyl radicals (see Part A, Table 11.3) favors addition in this case. 

Scheme 4.7 Generation of dihydrofurans from organomercury compounds.

SCHEME 27. Preparation of alkcnylzinc bromides from organomercurials... 

This route has, for example, been used to make the butyl compounds.15 The trimethylsilylmethyl derivatives have also been made1617 they can be precipitated from cyclohexane, washed free from organomercury starting materials, and obtained without organometal-alkoxide contaminants. Alternatively, KCH2SiMe3 may be used in situ, e.g., for metallation of alkenes.18... 

Alkenes from organomercurials.1 Photoinitiated reaction of diphenyl diselenide with the organomercurial 1 provides a mixture of the corresponding a- and P-phenyl selenides, which undergo oxidative elimination to 2. The reaction provides a key step in a total synthesis of K-76 (3), which counteracts the inflammatory... 

The interface to couple HPLC columns with the atomizer can be very simple, with a direct connection from the exit of the column to the nebulizer of the AAS or plasma detector. Unfortunately, the efficiency of the nebulizer is very low (1-3%), which limits the sensitivity. A general way to circumvent this lack of sensitivity is postcolumn derivatization to form cold Hg vapor. However, the generation of a cold vapor from organomercury species requires an extra step their conversion to... 

Over 35 years ago, Richard F. Heck found that olefins can insert into the metal-carbon bond of arylpalladium species generated from organomercury compounds [1], The carbopalladation of olefins, stoichiometric at first, was made catalytic by Tsutomu Mizoroki, who coupled aryl iodides with ethylene under high pressure, in the presence of palladium chloride and sodium carbonate to neutralize the hydroiodic acid formed (Scheme 1) [2], Shortly thereafter, Heck disclosed a more general and practical procedure for this transformation, using palladium acetate as the catalyst and tri-w-butyl amine as the base [3], After investigations on stoichiometric reactions by Fitton et al. [4], it was also Heck who introduced palladium phosphine complexes as catalysts, enabling the decisive extension of the ole-fination reaction to inexpensive aryl bromides [5],... 

Organomercurials are useful reagents for the synthesis of other organometallic complexes. Direct transmetallation is the most common approach and a large number of main group and transition metal organometallic complexes have been prepared in this way from organomercurials. 

Table 1. Organolithiums Prepared from Organomercurials with Li Metal ...

Organoalkalis are prepared from organomercurials with xs alkali metal, M ... 

It had been known from the work of Heck and Tsuji that certain organopalla-dium(II) species convert olefins into vinylic C-C-coupling products, with the active species being generated in situ from organomercurials and common palladium(II) salts [10]. The need for stoichiometric reagents, however, did not attract much interest from organic chemists. It was only the discovery that direct oxidative addi-... 

Dibromocarbene undergoes addition to alkenes in a stereospecific manner. The sole case of nonstereospecific dibromocyclopropanation using bromoform/base/phase-transfer catalyst concerns ( )-cyclooctene, and is explained by isomerization of this cycloalkene caused by reversible addition of tribromomethyl or ethoxide anion the latter is formed from the ethanol present in bromoform (see also ref 2 and Houben-Weyl, Vol. El 9b, p 1617 for stereomutation in the reactions of dibromocarbene, generated from organomercury reagents, with low-active alkenes, see Section 1.2.1.4.3.1.5.1. and Vol. E19b, pp 1615 1616). 

Table 1. Organogallanes Synthesized FROM Organomercurials with Ga Metal...

Table 1. Triorganoindanes Prepared from Organomercurials WITH In Metal...

Dienes, chelating reaction with metal atoms 5.S.2.5.3 Dienes, conjugated reaction with metal atoms 5.S.2.4.6 [-Dienyl complexes from organoaluminums 5.8.2.11.3 from organoborons 5.8.2.11.1 from organomercurials 5.8.2.11.2 from organotins 5.8.2.11.1... 

Oxidation of organomercury compounds via formation of TEMPO derivatives and cleavage with Zn-HOAc completes the functionalization of alkenes. Without TEMPO the oxidative capture of a primary radical generated from organomercurial is inefficient, and the reductive pathway (loss of functionality) becomes competitive. 

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