Cobalt chloride acylation

Bis(trimethylsilyl) sulphide reacts with acyl silanes in the presence of a cobalt chloride catalyst to afford the corresponding thiocarbonyl derivatives, thioacyl silanes (Scheme 100)214. The reaction is mild and proceeds in good yields. It is also applicable to aldehydes. Thioacyl silanes have been prepared from the corresponding haloacyl silanes by reaction with hydrogen sulphide (vide supra, Section IV.A.3)196. 

Acyl halides can also be converted to carboxylic acids by using ethers instead of alcohols, in MeCN in the presence of certain catalysts such as cobalt(II) chloride. ... 

The scope of this reaction is similar to that of 10-21. Though anhydrides are somewhat less reactive than acyl halides, they are often used to prepare carboxylic esters. Acids, Lewis acids, and bases are often used as catalysts—most often, pyridine. Catalysis by pyridine is of the nucleophilic type (see 10-9). 4-(A,A-Dimethylamino)pyridine is a better catalyst than pyridine and can be used in cases where pyridine fails. " Nonbasic catalysts are cobalt(II) chloride " and TaCls—Si02. " Formic anhydride is not a stable compound but esters of formic acid can be prepared by treating alcohols " or phenols " with acetic-formic anhydride. Cyclic anhydrides give monoesterified dicarboxylic acids, for example,... 

Oxiranes react with acyl chlorides, in presence of sodium iodide, to yield 2-iodoethyl esters1104. Cobalt(II) chloride is a catalyst in these reactions (equation 176)1105. 

In addition to alkyl, aryl and vinylcobalt/radical species, acid chlorides may be converted into acylcobalt species by reaction with the cobalt(I) salens. These generate acyl radicals under photolysis, which participate in similar reactions to the alkyl radicals in most cases (equations 184 and 185). Acylcobalt(III) species bearing an a-aryl or vinyl substituent, on the other hand, undergo concomitant decarbonylation to afford a benzylic or allyl radical, which then may undergo a number of bond-forming processes, including homocoupling361. 

Unsymmetrical, as well as symmetrical, anhydrides are often prepared by the treatment of an acyl halide with a carboxylic acid salt. Cobalt(II) chloride (C0CI2) has been used as a catalyst. If a metallic salt is used, Na+, K+, or Ag" are the most common cations, but more often pyridine or another tertiary amine is added to the free acid and the resulting salt is subsequently treated with the acyl halide. Mixed formic anhydrides are prepared from sodium formate and an aryl halide, by use of a solid-phase copolymer of pyridine-1-oxide. Symmetrical anhydrides can be prepared by reaction of the acyl halide with aq. NaOH or... 

The diene insertion reaction will take place intramolecularly if the diene system is part of the acyl group in the acylcobalt tetracarbonyl (13). Thus, /ra j-2,4-pentadienoyl(triphenylphosphine)cobalt tricarbonyl, prepared by the acid chloride method, cyclizes on heating in ether solution in a closed vessel at 75° C for an hour, to 7r-cyclopentenonyl(triphenylphosphine)cobalt dicarbonyl in 30% yield. 

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