Thioester

In chemistry thioesters are compounds with the functional group R–S–CO–R'. They are the product of esterification between a carboxylic acid and a thiol. In biochemistry, the best-known thioesters are derivatives of coenzyme A, e.g., acetyl-CoA.

The most typical route to thioester involves the reaction of an acid chloride with an alkali metal salt of a thiol:

Another common route entails the displacement of halides by the alkali metal salt of a thiocarboxylic acid. For example, thioacetate esters are commonly prepared by alkylation of potassium thioacetate:

The analogous alkylation of an acetate salt is rarely practiced. The alkylation can be conducted using Mannich bases and the thiocarboxylic acid:

Thioesters can be prepared by condensation of thiols and carboxylic acids in the presence of dehydrating agents:

A typical dehydration agent is DCC.Acid anhydrides and some lactones also give thioesters upon treatment with thiols in the presence of a base.

Thioesters can be conveniently prepared from alcohols by the Mitsunobu reaction, using thioacetic acid.

They also arise via carbonylation of alkynes and alkenes in the presence of thiols.

The carbonyl center in thioesters is reactive toward nucleophiles, even water. Thus, thioesters are common intermediates in the conversion of alkyl halides to alkyl thiols.Thioesters and amines combine to give amides:

Thioesters provide useful chemoselectivity in the synthesis of biomolecules.

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