Thioamide

Thioamide

Thioamide (rarely, thionamide) is a functional group with the general structure R-CS-NR'R", where R, R', and R" are organic groups. They are analogous to amides except that they exhibit greater multiple bond character between the C-N bond. One of the best known thioamides is thioacetamide, which is used as a source of the sulfide ion and is a building block in heterocyclic chemistry.

Preparation and structure

Thioamides are typically prepared by treating amides with phosphorus sulfides such as phosphorus pentasulfide and, in more specialized applications, Lawesson's reagent. [OrgSynth | author = R. Gompper, W. Elser | title = 2-Methylmercapto-N-Methyl-Δ2-Pyrroline | collvol = 5 | collvolpages = 780 | year = 1973 | prep = CV5P0780] [OrgSynth | author = George Schwarz | title = 2,4-Dimethylthiazole" Organic Syntheses | collvol = 3 | collvolpages = 332 | year = 1955 | prep = CV3P0332] An alternative route entails the reaction of nitriles with hydrogen sulfide. The Willgerodt-Kindler reaction reaction also affords benzylthioamides. [OrgSynth | author = Andreas Rolfs and Jürgen Liebscher | title = 3-Morpholino-2-Phenylthioacrylic Acid Morpholide and 5-(4-Bromobenzoyl-2-(4-Morpholino)-3-Phenylthiophene | collvol = 9 | collvolpages = 99 | year = 1998 | prep = CV9P0099]

Thioamides in biochemistry and medicine

Thioamides are also a class of drugs which are used to control thyrotoxicosis.

Thioamides have been incorporated into peptides as isosters for the amide bond. Peptide modifications are analogoues of the native peptide, which can reveal the structure-activity-relationship (SAR). Analogoues of peptides can also be used as drugs with an improved oral bioavailability. Thioamides inhibit the enzyme thyroid peroxidase in the thyroid, reducing the synthesis of triiodothyronine (T3) and thyroxine (T4); block uptake of iodotyrosines from the colloid. They also block iodine release from peripheral hormone. Maximum effects occur only after a month since hormone depletion is caused by reduced synthesis, which is a slow process.

An adverse effect of thioamides is that they penetrate the placental barrier, thus caution is advised when used during pregnancy. 10% of patients report skin eruptions (such as macules and papules), Urticaria, Dermatitis, Fever, and Arthralgia.Fact|date=November 2007 0.03% of all patients develop agranulocytosis, a dangerous side-effect.

Members of the thioamide group include Methimazole, Carbimazole converted "in vivo" to methimazole, and Propylthiouracil

References


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  • Thioamide — Un thioamide (nom commun masculin), appelé aussi une énaminothiocétone, est un composé organique portant le groupe représenté à droite. Il est l homologue du groupe amide dans lequel l atome d oxygène a été substitué par un atome de soufre.… …   Wikipédia en Français

  • thioamide — tioamidas statusas T sritis chemija formulė RC(=S)NH₂ atitikmenys: angl. thioamide rus. тиоамид …   Chemijos terminų aiškinamasis žodynas

  • thioamide — noun Any chemical compound, analogous to the amides in which the oxygen atom of the carbonyl group is replaced by sulfur; R CS NH (and N derivatives) …   Wiktionary

  • thioamide — An amide in which S replaces O. * * * thio·amide am .īd, əd n an amide of a thio acid esp an amide having the general formula RCSNH2 …   Medical dictionary

  • thioamide — thio·amide …   English syllables

  • thioamide — /θaɪoʊˈæmaɪd/ (say thuyoh amuyd), / ˈæməd/ (say amuhd) noun a compound containing the C(NH2)=S group. See polyamide …  

  • thioamide — “+ noun Etymology: International Scientific Vocabulary thi + amide : an amide of a thio acid; especially : an amide having the general formula RCSNH2 and made usually by the reaction of an amide of a carboxylic acid with phosphorus pentasulfide… …   Useful english dictionary

  • Groupe fonctionnel — En chimie organique, un groupe fonctionnel est une structure sub moléculaire constituée d un assemblage d atomes donnés qui confère une réactivité propre à la molécule qui le contient. Cette manière de considérer les molécules comme étant un… …   Wikipédia en Français

  • Thiourea — Chembox new ImageFile=thiourea.png ImageSize= ImageFile2=Thiourea 3D vdW.png IUPACName=thiourea OtherNames= Section1= Chembox Identifiers CASNo=62 56 6 PubChem=2723790 SMILES=C(=S)(N)N Section2= Chembox Properties Formula=CH4N2S MolarMass=76.1219 …   Wikipedia

  • Methimazole — Not to be confused with metamizole . Methimazole Systematic (IUPAC) name 1 methyl 3H imidazole 2 thione Clinical data …   Wikipedia

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