Thiolactones are a class of

heterocyclic compounds A heterocyclic compound or ring structure is a cyclic compound that has atoms of at least two different elements as members of its ring(s). Heterocyclic chemistry is the branch of organic chemistry dealing with the synthesis, properties, and ...

organic chemistry Organic chemistry is a subdiscipline within chemistry involving the scientific study of the structure, properties, and reactions of organic compounds and organic materials, i.e., matter in its various forms that contain carbon atoms.Clayden, J.; ...

. They are analogs of the more common

lactone Lactones are cyclic carboxylic esters, containing a 1-oxacycloalkan-2-one structure (), or analogues having unsaturation or heteroatoms replacing one or more carbon atoms of the ring. Lactones are formed by intramolecular esterification of the co ...

s in which an oxygen atom is replaced with a sulfur atom. The sulfur atom is within the ring system and adjacent to a

carbonyl group In organic chemistry, a carbonyl group is a functional group composed of a carbon atom double-bonded to an oxygen atom: C=O. It is common to several classes of organic compounds, as part of many larger functional groups. A compound containing a ...

Chemistry

Thiolactones can be prepared by

dehydration In physiology, dehydration is a lack of total body water, with an accompanying disruption of metabolic processes. It occurs when free water loss exceeds free water intake, usually due to exercise, disease, or high environmental temperature. Mil ...

of thiol-containing carboxylic acids. Thiolactones can be

hydrolyzed Hydrolysis (; ) is any chemical reaction in which a molecule of water breaks one or more chemical bonds. The term is used broadly for substitution, elimination, and solvation reactions in which water is the nucleophile. Biological hydrolysis ...

back to the thiol acids under basic conditions. β-Thiolactones can be opened by reaction at the 4-position via S_N2 nucleophilic reactions.

Occurrence

The most common thiolactone,

homocysteine thiolactone Homocysteine is a non-proteinogenic α-amino acid. It is a homologue of the amino acid cysteine, differing by an additional methylene bridge (-CH2-). It is biosynthesized from methionine by the removal of its terminal Cε methyl group. In the ...

is produced biochemically from

homocysteine Homocysteine is a non-proteinogenic α-amino acid. It is a homologue of the amino acid cysteine, differing by an additional methylene bridge (-CH2-). It is biosynthesized from methionine by the removal of its terminal Cε methyl group. In the b ...

and it may play a role in protein damage. The thiolactone functional group is also present in some pharmaceutical drugs such as

citiolone Citiolone is a drug used in liver therapy. It is a derivative of the amino acid cysteine. Citilone has also been studied with regards to hypothermia due to it being a hydroxyl free radical scavenger. The drug has been shown to protect hamster ...

and

erdosteine Erdosteine is a molecule with mucolytic activity. Structurally it is a thiol derivative characterized by the presence of two thiol groups. These two functional sulfhydryl groups contained in the molecule are released following first-pass metabol ...

. Thiolactone rings can also be found in peptides synthesized by bacteria such as ''

Staphylococcus aureus ''Staphylococcus aureus'' is a Gram-positive spherically shaped bacterium, a member of the Bacillota, and is a usual member of the microbiota of the body, frequently found in the upper respiratory tract and on the skin. It is often positive ...

'' in order to regulate their quorum-sensing system.

References

{{reflist Functional groups

Chemistry

Occurrence

See also

References