Organomercury reagents acylation

Organomercury reagents do not react with ketones or aldehydes but Lewis acids cause reaction with acyl chlorides.187 With alkenyl mercury compounds, the reaction probably proceeds by electrophilic attack on the double bond with the regiochemistry being directed by the stabilization of the (3-carbocation by the mercury.188... 

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. 

The relatively low reactivity of the RHgX reagent is shown by acylation with RCOCl this gives a ketone that is stable to further attack by the or-ganometallic species. The organomercury reagents with their very weak Hg—C bonds are a useful source of radicals. Once the first R is released, the remaining R is very weakly bound (Eq. 14.31) and so both radicals are effectively released at the same time. 

Carboxylic acids may be activated towards attack by Grignard reagents by chloroiminium salts [equation (4)]. Copper(i) additives improve the yield of the ketone. Under the reaction conditions, esters and ketals are unaffected. The acylation of organomercurials to give ketones has been reviewed. ... 

---