2-''sec''-Butyl-4,5-dihydrothiazole (also known as SBT) is a

thiazoline Thiazolines (; or dihydrothiazoles) are a group of isomeric 5-membered heterocyclic compounds containing both sulfur and nitrogen in the ring. Although unsubstituted thiazolines are rarely encountered themselves, their derivative (chemistry), der ...

compound with the molecular formula C₇H₁₃NS. A volatile

pheromone A pheromone () is a secreted or excreted chemical factor that triggers a social response in members of the same species. Pheromones are chemicals capable of acting like hormones outside the body of the secreting individual, to affect the behavio ...

found in

rodents Rodents (from Latin , 'to gnaw') are mammals of the order Rodentia ( ), which are characterized by a single pair of continuously growing incisors in each of the upper and lower jaws. About 40% of all mammal species are rodents. They are n ...

such as

mice A mouse (: mice) is a small rodent. Characteristically, mice are known to have a pointed snout, small rounded ears, a body-length scaly tail, and a high breeding rate. The best known mouse species is the common house mouse (''Mus musculus' ...

and

rat Rats are various medium-sized, long-tailed rodents. Species of rats are found throughout the order Rodentia, but stereotypical rats are found in the genus ''Rattus''. Other rat genera include '' Neotoma'' (pack rats), '' Bandicota'' (bandicoo ...

s, SBT is excreted in the urine and promotes aggression amongst males while inducing synchronized estrus in females.

Binding to MUP

Mouse

major urinary proteins Major urinary proteins (Mups), also known as α2u-globulins, are a protein subfamily, subfamily of proteins found in abundance in the urine and other secretions of many animals. Mups provide a small range of identifying information about the don ...

(MUPs) are responsible for binding to hydrophobic

ligands In coordination chemistry, a ligand is an ion or molecule with a functional group that binds to a central metal atom to form a coordination complex. The bonding with the metal generally involves formal donation of one or more of the ligand's ...

such as the pheromone SBT. SBT binds within MUP-I's barrel-shaped active site, forming a

hydrogen bond In chemistry, a hydrogen bond (H-bond) is a specific type of molecular interaction that exhibits partial covalent character and cannot be described as a purely electrostatic force. It occurs when a hydrogen (H) atom, Covalent bond, covalently b ...

with a water molecule within the

active site In biology and biochemistry, the active site is the region of an enzyme where substrate molecules bind and undergo a chemical reaction. The active site consists of amino acid residues that form temporary bonds with the substrate, the ''binding s ...

, which in turn is stabilized by forming hydrogen bonds with residue Phe56 and another water molecule; this second water molecule also forms hydrogen bonds to residues in the active site, namely Leu58 and Thr39. SBT also forms

van der Waals forces In molecular physics and chemistry, the van der Waals force (sometimes van der Waals' force) is a distance-dependent interaction between atoms or molecules. Unlike ionic or covalent bonds, these attractions do not result from a chemical ele ...

with several of MUP-I's residues, including Ala121, Leu123, Leu134, Leu72, Val100, and Phe108. When bound, MUP safely carries SBT through the aqueous environment; once the protein-ligand complex is excreted in the urine, MUP helps prevent SBT decomposition and controls the slow release of SBT over a prolonged period of time, resulting in the physiological and behavioral responses of animals who come into contact with the pheromone.

Synthesis

SBT can be produced from 3-(2-aminoethanethio)-4-methylhex-2-enenitrile; however, it is also possible to synthesize SBT from

ethanolamine Ethanolamine (2-aminoethanol, monoethanolamine, ETA, or MEA) is a naturally occurring organic chemical compound with the formula or . The molecule is bifunctional, containing both a primary amine and a primary alcohol. Ethanolamine is a colorl ...

and

2-methylbutanoic acid 2-Methylbutanoic acid, also known as 2-methylbutyric acid is a branched-chain alkyl carboxylic acid with the chemical formula CH3CH2CH(CH3)CO2H, classified as a short-chain fatty acid. It exists in two enantiomeric forms, (''R'')- and (''S'')-2-m ...

, using

Lawesson's reagent Lawesson's reagent (LR) is a chemical compound used in organic synthesis as a thiation agent. Lawesson's reagent was first made popular by Sven-Olov Lawesson, who did not, however, invent it. Lawesson's reagent was first made in 1956 during a sy ...

and microwave irradiation.

References

{{DEFAULTSORT:Butyl-4,5-dihydrothiazole, 2-sec- Mammalian pheromones Thiazolines Sec-Butyl compounds