Thiolactone
Encyclopedia
Thiolactones are a class of heterocyclic compounds in organic chemistry
. They are analogs of the more common lactone
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.
of thiol-containing carboxylic acids. Thiolactones can be hydrolyzed
back to the thiol acids under basic conditions. β-Thiolactones can be opened by reaction at the 4-position via SN2 nucleophilic reactions
.
and it may play a role in protein damage. The thiolactone functional group is also present in some pharmaceutical drugs such as citiolone
and erdosteine
.
Organic chemistry
Organic chemistry is a subdiscipline within chemistry involving the scientific study of the structure, properties, composition, reactions, and preparation of carbon-based compounds, hydrocarbons, and their derivatives...
. They are analogs of the more common lactone
Lactone
In chemistry, a lactone is a cyclic ester which can be seen as the condensation product of an alcohol group -OH and a carboxylic acid group -COOH in the same molecule...
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.
Chemistry
Thiolactones can be prepared by dehydrationDehydration reaction
In chemistry and the biological sciences, a dehydration reaction is usually defined as a chemical reaction that involves the loss of water from the reacting molecule. Dehydration reactions are a subset of elimination reactions...
of thiol-containing carboxylic acids. Thiolactones can be hydrolyzed
Hydrolysis
Hydrolysis is a chemical reaction during which molecules of water are split into hydrogen cations and hydroxide anions in the process of a chemical mechanism. It is the type of reaction that is used to break down certain polymers, especially those made by condensation polymerization...
back to the thiol acids under basic conditions. β-Thiolactones can be opened by reaction at the 4-position via SN2 nucleophilic reactions
SN2 reaction
The SN2 reaction is a type of nucleophilic substitution, where a lone pair from a nucleophile attacks an electron deficient electrophilic center and bonds to it, expelling another group called a leaving group. Thus the incoming group replaces the leaving group in one step...
.
Occurrence
The most common thiolactone, homocysteine thiolactone is produced biochemically from homocysteineHomocysteine
Homocysteine is a non-protein amino acid with the formula HSCH2CH2CHCO2H. It is a homologue of the amino acid cysteine, differing by an additional methylene group. It is biosynthesized from methionine by the removal of its terminal Cε methyl group...
and it may play a role in protein damage. The thiolactone functional group is also present in some pharmaceutical drugs such as citiolone
Citiolone
Citiolone is a drug used in liver therapy. It is a derivative of the amino acid cysteine....
and erdosteine
Erdosteine
Erdosteine is a mucolytic. Specifically it is a thiol derivative developed for the treatment of chronic obstructive bronchitis, including acute infective exacerbation of chronic bronchitis. Erdosteine contains two blocked sulfhydryl groups which are released following first-pass metabolism. The...
.