Pyrimidine

Aromatic compound (C4H4N2)

Not to be confused with Pyridine.

Pyrimidine  |  |

|

|  |

|

Names
Preferred IUPAC name

Pyrimidine[1]

Systematic IUPAC name

1,3-Diazabenzene

Other names

1,3-Diazine
m-Diazine

Identifiers

CAS Number

* 289-95-2 Y

3D model (JSmol)

* Interactive image

ChEBI |

* CHEBI:16898 Y

ChEMBL |

* ChEMBL15562 Y

ChemSpider |

* 8903 Y

ECHA InfoCard | 100.005.479
KEGG |

* C00396 Y

MeSH | pyrimidine

PubChem CID

* 9260

UNII |

* K8CXK5Q32L Y

CompTox Dashboard (EPA)

* DTXSID1051228

InChI

* InChI=1S/C4H4N2/c1-2-5-4-6-3-1/h1-4H Y

Key: CZPWVGJYEJSRLH-UHFFFAOYSA-N Y

* InChI=1/C4H4N2/c1-2-5-4-6-3-1/h1-4H

Key: CZPWVGJYEJSRLH-UHFFFAOYAT

SMILES

* n1cnccc1

Properties

Chemical formula

| C4H4N2
Molar mass | 80.088 g mol−1
Density | 1.016 g cm−3
Melting point | 20 to 22 °C (68 to 72 °F; 293 to 295 K)
Boiling point | 123 to 124 °C (253 to 255 °F; 396 to 397 K)

Solubility in water

| Miscible (25°C)
Acidity (pKa)  | 1.10[2] (protonated pyrimidine)

Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).

Y verify (what is YN ?)

Infobox references

Chemical compound

Pyrimidine (C4H4N2; /pɪˈrɪ.mɪˌdiːn, paɪˈrɪ.mɪˌdiːn/) is an aromatic, heterocyclic, organic compound similar to pyridine (C5H5N).[3] One of the three diazines (six-membered heterocyclics with two nitrogen atoms in the ring), it has nitrogen atoms at positions 1 and 3 in the ring.[4]: 250 The other diazines are pyrazine (nitrogen atoms at the 1 and 4 positions) and pyridazine (nitrogen atoms at the 1 and 2 positions).

In nucleic acids, three types of nucleobases are pyrimidine derivatives: cytosine (C), thymine (T), and uracil (U).

## Occurrence and history[edit]

Pinner's 1885 structure for pyrimidine

The pyrimidine ring system has wide occurrence in nature[5] as substituted and ring fused compounds and derivatives, including the nucleotides cytosine, thymine and uracil, thiamine (vitamin B1) and alloxan. It is also found in many synthetic compounds such as barbiturates and the HIV drug zidovudine. Although pyrimidine derivatives such as alloxan were known in the early 19th century, a laboratory synthesis of a pyrimidine was not carried out until 1879,[5] when Grimaux reported the preparation of barbituric acid from urea and malonic acid in the presence of phosphorus oxychloride.[6] The systematic study of pyrimidines began[7] in 1884 with Pinner,[8] who synthesized derivatives by condensing ethyl acetoacetate with amidines. Pinner first proposed the name “pyrimidin” in 1885.[9] The parent compound was first prepared by Gabriel and Colman in 1900,[10] [11] by conversion of barbituric acid to 2,4,6-trichloropyrimidine followed by reduction using zinc dust in hot water.

## Nomenclature[edit]

The nomenclature of pyrimidines is straightforward. However, like other heterocyclics, tautomeric hydroxyl groups yield complications since they exist primarily in the cyclic amide form. For example, 2-hydroxypyrimidine is more properly named 2-pyrimidone. A partial list of trivial names of various pyrimidines exists.[12]: 5–6

## Physical properties[edit]

Physical properties are shown in the data box. A more extensive discussion, including spectra, can be found in Brown et al.[12]: 242–244

## Chemical properties[edit]

Per the classification by Albert[13]: 56–62 six-membered heterocycles can be described as π-deficient. Substitution by electronegative groups or additional nitrogen atoms in the ring significantly increase the π-deficiency. These effects also decrease the basicity.[13]: 437–439

Like pyridines, in pyrimidines the π-electron density is decreased to an even greater extent. Therefore, electrophilic aromatic substitution is more difficult while nucleophilic aromatic substitution is facilitated. An example of the last reaction type is the displacement of the amino group in 2-aminopyrimidine by chlorine[14] and its reverse.[15]

Electron lone pair availability (basicity) is decreased compared to pyridine. Compared to pyridine, N-alkylation and N-oxidation are more difficult. The pKa value for protonated pyrimidine is 1.23 compared to 5.30 for pyridine. Protonation and other electrophilic additions will occur at only one nitrogen due to further deactivation by the second nitrogen.[4]: 250 The 2-, 4-, and 6- positions on the pyrimidine ring are electron deficient analogous to those in pyridine and nitro- and dinitrobenzene. The 5-position is less electron deficient and substituents there are quite stable. However, electrophilic substitution is relatively facile at the 5-position, including nitration and halogenation.[12]: 4–8

Reduction in resonance stabilization of pyrimidines may lead to addition and ring cleavage reactions rather than substitutions. One such manifestation is observed in the Dimroth rearrangement.

Pyrimidine is also found in meteorites, but scientists still do not know its origin. Pyrimidine also photolytically decomposes into uracil under ultraviolet light.[16]

## Synthesis[edit]

Pyrimidine biosynthesis creates derivatives —like orotate, thymine, cytosine, and uracil— de novo from carbamoyl phosphate and aspartate.

As is often the case with parent heterocyclic ring systems, the synthesis of pyrimidine is not that common and is usually performed by removing functional groups from derivatives. Primary syntheses in quantity involving formamide have been reported.[12]: 241–242

As a class, pyrimidines are typically synthesized by the principal synthesis involving cyclization of β-dicarbonyl compounds with N–C–N compounds. Reaction of the former with amidines to give 2-substituted pyrimidines, with urea to give 2-pyrimidinones, and guanidines to give 2-aminopyrimidines are typical.[12]: 149–239

Pyrimidines can be prepared via the Biginelli reaction and other multicomponent reactions.[17] Many other methods rely on condensation of carbonyls with diamines for instance the synthesis of 2-thio-6-methyluracil from thiourea and ethyl acetoacetate[18] or the synthesis of 4-methylpyrimidine with 4,4-dimethoxy-2-butanone and formamide.[19]

A novel method is by reaction of N-vinyl and N-aryl amides with carbonitriles under electrophilic activation of the amide with 2-chloro-pyridine and trifluoromethanesulfonic anhydride:[20]

## Reactions[edit]

Because of the decreased basicity compared to pyridine, electrophilic substitution of pyrimidine is less facile. Protonation or alkylation typically takes place at only one of the ring nitrogen atoms. Mono-N-oxidation occurs by reaction with peracids.[4]: 253–254

Electrophilic C-substitution of pyrimidine occurs at the 5-position, the least electron-deficient. Nitration, nitrosation, azo coupling, halogenation, sulfonation, formylation, hydroxymethylation, and aminomethylation have been observed with substituted pyrimidines.[12]: 9–13

Nucleophilic C-substitution should be facilitated at the 2-, 4-, and 6-positions but there are only a few examples. Amination and hydroxylation have been observed for substituted pyrimidines. Reactions with Grignard or alkyllithium reagents yield 4-alkyl- or 4-aryl pyrimidine after aromatization.[12]: 14–15

Free radical attack has been observed for pyrimidine and photochemical reactions have been observed for substituted pyrimidines.[12]: 15–16 Pyrimidine can be hydrogenated to give tetrahydropyrimidine.[12]: 17

## Derivatives[edit]

Pyrimidine derivatives  Formula | Name | Structure | C2 | C4 | C5 | C6

|
|
|
|
|
|

C4H5N3O | cytosine |  | =O | –NH2 | –H | –H
C4H4N2O2 | uracil | =O | =O | –H | –H
C4H3FN2O2 | fluorouracil | =O | =O | –F | –H
C5H6N2O2 | thymine | =O | =O | –CH3 | –H
C4H4N2O3 | barbituric acid | =O | =O | –H | =O
C5H4N2O4 | orotic acid | =O | =O | –H | -COOH

### Nucleotides[edit]

The pyrimidine nitrogen bases found in DNA and RNA.

Three nucleobases found in nucleic acids, cytosine (C), thymine (T), and uracil (U), are pyrimidine derivatives:

Chemical structure of cytosine | Chemical structure of thymine | Chemical structure of uracil

|
|

Cytosine (C)

Thymine (T)

Uracil (U)

In DNA and RNA, these bases form hydrogen bonds with their complementary purines. Thus, in DNA, the purines adenine (A) and guanine (G) pair up with the pyrimidines thymine (T) and cytosine (C), respectively.

In RNA, the complement of adenine (A) is uracil (U) instead of thymine (T), so the pairs that form are adenine:uracil and guanine:cytosine.

Very rarely, thymine can appear in RNA, or uracil in DNA, but when the other three major pyrimidine bases are represented, some minor pyrimidine bases can also occur in nucleic acids. These minor pyrimidines are usually methylated versions of major ones and are postulated to have regulatory functions.[21]

These hydrogen bonding modes are for classical Watson–Crick base pairing. Other hydrogen bonding modes ("wobble pairings") are available in both DNA and RNA, although the additional 2′-hydroxyl group of RNA expands the configurations, through which RNA can form hydrogen bonds.[22]

## Theoretical aspects[edit]

In March 2015, NASA Ames scientists reported that, for the first time, complex DNA and RNA organic compounds of life, including uracil, cytosine and thymine, have been formed in the laboratory under outer space conditions, using starting chemicals, such as pyrimidine, found in meteorites. Pyrimidine, like polycyclic aromatic hydrocarbons (PAHs), the most carbon-rich chemical found in the universe, may have been formed in red giants or in interstellar dust and gas clouds.[23][24][25]

### Prebiotic synthesis of pyrimidine nucleotides[edit]

In order to understand how life arose, knowledge is required of the chemical pathways that permit formation of the key building blocks of life under plausible prebiotic conditions. The RNA world hypothesis holds that in the primordial soup there existed free-floating ribonucleotides, the fundamental molecules that combine in series to form RNA. Complex molecules such as RNA must have emerged from relatively small molecules whose reactivity was governed by physico-chemical processes. RNA is composed of pyrimidine and purine nucleotides, both of which are necessary for reliable information transfer, and thus natural selection and Darwinian evolution. Becker et al. showed how pyrimidine nucleosides can be synthesized from small molecules and ribose, driven solely by wet-dry cycles.[26] Purine nucleosides can be synthesized by a similar pathway. 5’-mono-and diphosphates also form selectively from phosphate-containing minerals, allowing concurrent formation of polyribonucleotides with both the pyrimidine and purine bases. Thus a reaction network towards the pyrimidine and purine RNA building blocks can be established starting from simple atmospheric or volcanic molecules.

## See also[edit]

* ANRORC mechanism
* Purine
* Pyrimidine metabolism
* Simple aromatic rings
* Transition
* Transversion

## References[edit]

1. ^ "Front Matter". Nomenclature of Organic Chemistry : IUPAC Recommendations and Preferred Names 2013 (Blue Book). Cambridge: The Royal Society of Chemistry. 2014. p. 141\. doi:10.1039/9781849733069-FP001. ISBN 978-0-85404-182-4.
2. ^ Brown, H. C.; et al. (1955). Baude, E. A.; F. C., Nachod (eds.). Determination of Organic Structures by Physical Methods. New York, NY: Academic Press.
3. ^ Gilchrist, Thomas Lonsdale (1997). Heterocyclic chemistry. New York: Longman. ISBN 978-0-582-27843-1.
4. ^ a b c Joule, John A.; Mills, Keith, eds. (2010). Heterocyclic Chemistry (5th ed.). Oxford: Wiley. ISBN 978-1-405-13300-5.
5. ^ a b Lagoja, Irene M. (2005). "Pyrimidine as Constituent of Natural Biologically Active Compounds" (PDF). Chemistry and Biodiversity. 2 (1): 1–50. doi:10.1002/cbdv.200490173. PMID 17191918. S2CID 9942715.
6. ^ Grimaux, E. (1879). "Synthèse des dérivés uriques de la série de l'alloxane" [Synthesis of urea derivatives of the alloxan series]. Comptes Rendus Hebdomadaires des Séances de l'Académie des Sciences. 88: 85–87.
7. ^ Kenner, G. W.; Todd, Alexander (1957). Elderfield, R.C. (ed.). Heterocyclic Compounds. Vol. 6\. New York: Wiley. p. 235.
8. ^ Pinner, A. (1884). "Ueber die Einwirkung von Acetessigäther auf die Amidine" [On the effect of acetylacetonate ester on amidines]. Berichte der Deutschen Chemischen Gesellschaft. A17 (2): 2519–2520. doi:10.1002/cber.188401702173.
9. ^ Pinner, A. (1885). "Ueber die Einwirkung von Acetessigäther auf die Amidine. Pyrimidin" [On the effect of acetylacetonate ester on amidines. Pyrimidine]. Berichte der Deutschen Chemischen Gesellschaft. A18: 759–760. doi:10.1002/cber.188501801161.
10. ^ Gabriel, S. (1900). "Pyrimidin aus Barbitursäure" [Pyrimidine from barbituric acid]. Berichte der Deutschen Chemischen Gesellschaft. A33 (3): 3666–3668. doi:10.1002/cber.190003303173.
11. ^ Lythgoe, B.; Rayner, L. S. (1951). "Substitution Reactions of Pyrimidine and its 2- and 4-Phenyl Derivatives". Journal of the Chemical Society. 1951: 2323–2329. doi:10.1039/JR9510002323.
12. ^ a b c d e f g h i Brown, D. J.; Evans, R. F.; Cowden, W. B.; Fenn, M. D. (1994). The Pyrimidines. New York, NY: John Wiley & Sons. ISBN 978-0-471-50656-0.
13. ^ a b Albert, Adrien (1968). Heterocyclic Chemistry, an Introduction. London: Athlone Press.
14. ^ Kogon, Irving C.; Minin, Ronald; Overberger, C. G. "2-Chloropyrimidine". Organic Syntheses. 35: 34. doi:10.15227/orgsyn.035.0034.; Collective Volume, vol. 4, p. 182
15. ^ Overberger, C. G.; Kogon, Irving C.; Minin, Ronald. "2-(Dimethylamino)pyrimidine". Organic Syntheses. 35: 58. doi:10.15227/orgsyn.035.0058.; Collective Volume, vol. 4, p. 336
16. ^ Nuevo, M.; Milam, S. N.; Sandford, S. A.; Elsila, J. E.; Dworkin, J. P. (2009). "Formation of uracil from the ultraviolet photo-irradiation of pyrimidine in pure H2O ices". Astrobiology. 9 (7): 683–695. Bibcode:2009AsBio...9..683N. doi:10.1089/ast.2008.0324. PMID 19778279.
17. ^ Anjirwala, Sharmil N.; Parmar, Parnas S.; Patel, Saurabh K. (28 October 2022). "Synthetic protocols for non-fused pyrimidines". Synthetic Communications. 52 (22): 2079–2121. doi:10.1080/00397911.2022.2137682. S2CID 253219218.
18. ^ Foster, H. M.; Snyder, H. R. "4-Methyl-6-hydroxypyrimidine". Organic Syntheses. 35: 80. doi:10.15227/orgsyn.035.0080.; Collective Volume, vol. 4, p. 638
19. ^ Bredereck, H. "4-methylpyrimidine". Organic Syntheses. 43: 77. doi:10.15227/orgsyn.043.0077.; Collective Volume, vol. 5, p. 794
20. ^ Movassaghi, Mohammad; Hill, Matthew D. (2006). "Single-Step Synthesis of Pyrimidine Derivatives". J. Am. Chem. Soc. 128 (44): 14254–14255. doi:10.1021/ja066405m. PMID 17076488.
21. ^ Nelson, David L.; Cox, Michael M. (2008). Principles of Biochemistry (5th ed.). W. H. Freeman. pp. 272–274. ISBN 978-1429208925.
22. ^ PATIL, SHARANABASAPPA B.; P., GOURAMMA; JALDE, SHIVAKUMAR S. (2021-07-15). "Medicinal Significance of Novel Coumarins: A Review". International Journal of Current Pharmaceutical Research: 1–5. doi:10.22159/ijcpr.2021v13i4.42733. ISSN 0975-7066. S2CID 238840705.
23. ^ Marlaire, Ruth (3 March 2015). "NASA Ames reproduces the building blocks of life in laboratory" (Press release). NASA. Retrieved 5 March 2015.
24. ^ Nuevo, M.; Chen, Y. J.; Hu, W. J.; Qiu, J. M.; Wu, S. R.; Fung, H. S.; Yih, T. S.; Ip, W. H.; Wu, C. Y. R. (2014). "Photo-irradiation of pyrimidine in pure H2O ice with high-energy ultraviolet photons" (PDF). Astrobiology. 14 (2): 119–131. Bibcode:2014AsBio..14..119N. doi:10.1089/ast.2013.1093. PMC 3929345. PMID 24512484.
25. ^ Sandford, S. A.; Bera, P. P.; Lee, T. J.; Materese, C. K.; Nuevo, M. (6 February 2014). Photosynthesis and photo-stability of nucleic acids in prebiotic extraterrestrial environments (PDF). Topics in Current Chemistry. Vol. 356\. pp. 123–164. Bibcode:2014ppna.book..123S. doi:10.1007/128_2013_499. ISBN 978-3-319-13271-6. PMC 5737941. PMID 24500331. `{{cite book}}`: `|journal=` ignored (help), also published as Barbatti, M.; Borin, A. C.; Ullrich, S. (eds.). "14: Photosynthesis and photo-stability of nucleic acids in prebiotic extraterrestrial environments". Photoinduced phenomena in nucleic acids. Berlin, Heidelberg: Springer-Verlag. p. 499.
26. ^ Becker S, Feldmann J, Wiedemann S, Okamura H, Schneider C, Iwan K, Crisp A, Rossa M, Amatov T, Carell T. Unified prebiotically plausible synthesis of pyrimidine and purine RNA ribonucleotides. Science. 2019 Oct 4;366(6461):76-82. doi: 10.1126/science.aax2747. PMID 31604305

* v
* t
* e

Nucleic acid constituents

Nucleobase|

* Purine
* Adenine
* Guanine
* Hypoxanthine
* Xanthine
* Purine analogue
* Pyrimidine
* Uracil
* Thymine
* Cytosine
* Pyrimidine analogue
* Unnatural base pair (UBP)

Nucleoside|

| Ribonucleoside|

* Adenosine
* Guanosine
* 5-Methyluridine
* Uridine
* 5-Methylcytidine
* Cytidine
* Pseudouridine
* Inosine
* N6-Methyladenosine
* Xanthosine
* Wybutosine

|

Deoxyribonucleoside|

* Deoxyadenosine
* Deoxyguanosine
* Thymidine
* Deoxyuridine
* Deoxycytidine
* Deoxyinosine
* Deoxyxanthosine

Nucleotide
(Nucleoside monophosphate)|

| Ribonucleotide|

* AMP
* GMP
* m5UMP
* UMP
* CMP
* IMP
* XMP

|

Deoxyribonucleotide|

* dAMP
* dGMP
* dTMP
* dUMP
* dCMP
* dIMP
* dXMP

Cyclic nucleotide|

* cAMP
* cGMP
* c-di-GMP
* c-di-AMP
* cADPR
* cGAMP

Nucleoside diphosphate|

* ADP
* GDP
* m5UDP
* UDP
* CDP

* dADP
* dGDP
* dTDP
* dUDP
* dCDP

Nucleoside triphosphate|

* ATP
* GTP
* m5UTP
* UTP
* CTP
* ITP
* XTP

* dATP
* dGTP
* dTTP
* dUTP
* dCTP
* dITP
* dXTP

* v
* t
* e

Molecules detected in outer space

Molecules|

| Diatomic|

* Aluminium monochloride
* Aluminium monofluoride
* Aluminium(II) oxide
* Argonium
* Carbon cation
* Carbon monophosphide
* Carbon monosulfide
* Carbon monoxide
* Cyano radical
* Diatomic carbon
* Fluoromethylidynium
* Helium hydride ion
* Hydrogen chloride
* Hydrogen fluoride
* Hydrogen (molecular)
* Hydroxyl radical
* Iron(II) oxide
* Magnesium monohydride
* Methylidyne radical
* Nitric oxide
* Nitrogen (molecular)
* Imidogen
* Sulfur mononitride
* Oxygen (molecular)
* Phosphorus monoxide
* Phosphorus mononitride
* Potassium chloride
* Silicon carbide
* Silicon monoxide
* Silicon monosulfide
* Sodium chloride
* Sodium iodide
* Sulfur monohydride
* Sulfur monoxide
* Titanium(II) oxide

|
|

Triatomic|

* Aluminium(I) hydroxide
* Aluminium isocyanide
* Amino radical
* Carbon dioxide
* Carbonyl sulfide
* CCP radical
* Chloronium
* Diazenylium
* Dicarbon monoxide
* Disilicon carbide
* Ethynyl radical
* Formyl radical
* Hydrogen cyanide (HCN)
* Hydrogen isocyanide (HNC)
* Hydrogen sulfide
* Hydroperoxyl
* Iron cyanide
* Isoformyl
* Magnesium cyanide
* Magnesium isocyanide
* Methylene radical
* N2H+
* Nitrous oxide
* Nitroxyl
* Ozone
* Phosphaethyne
* Potassium cyanide
* Protonated molecular hydrogen
* Sodium cyanide
* Sodium hydroxide
* Silicon carbonitride
* c-Silicon dicarbide
* SiNC
* Sulfur dioxide
* Thioformyl
* Thioxoethenylidene
* Titanium dioxide
* Tricarbon
* Water

Four
atoms|

* Acetylene
* Ammonia
* Cyanic acid
* Cyanoethynyl
* Formaldehyde
* Fulminic acid
* HCCN
* Hydrogen peroxide
* Hydromagnesium isocyanide
* Isocyanic acid
* Isothiocyanic acid
* Ketenyl
* Methylene amidogen
* Methyl cation
* Methyl radical
* Propynylidyne
* Protonated carbon dioxide
* Protonated hydrogen cyanide
* Silicon tricarbide
* Thioformaldehyde
* Tricarbon monoxide
* Tricarbon monosulfide
* Thiocyanic acid

Five
atoms|

* Ammonium ion
* Butadiynyl
* Carbodiimide
* Cyanamide
* Cyanoacetylene
* Cyanoformaldehyde
* Cyanomethyl
* Cyclopropenylidene
* Formic acid
* Isocyanoacetylene
* Ketene
* Methane
* Methoxy radical
* Methylenimine
* Propadienylidene
* Protonated formaldehyde
* Silane
* Silicon-carbide cluster

Six
atoms|

* Acetonitrile
* Cyanobutadiynyl radical
* E-Cyanomethanimine
* Cyclopropenone
* Diacetylene
* Ethylene
* Formamide
* HC4N
* Ketenimine
* Methanethiol
* Methanol
* Methyl isocyanide
* Pentynylidyne
* Propynal
* Protonated cyanoacetylene

Seven
atoms|

* Acetaldehyde
* Acrylonitrile
* Vinyl cyanide
* Cyanodiacetylene
* Ethylene oxide
* Glycolonitrile
* Hexatriynyl radical
* Methylacetylene
* Methylamine
* Methyl isocyanate
* Vinyl alcohol

Eight
atoms|

* Acetic acid
* Aminoacetonitrile
* Cyanoallene
* Ethanimine
* Glycolaldehyde
* Hexapentaenylidene
* Methylcyanoacetylene
* Methyl formate
* Propenal

Nine
atoms|

* Acetamide
* Cyanohexatriyne
* Cyanotriacetylene
* Dimethyl ether
* Ethanol
* Methyldiacetylene
* Octatetraynyl radical
* Propene
* Propionitrile

Ten
atoms
or more|

* Acetone
* Benzene
* Benzonitrile
* Buckminsterfullerene (C60, C60+, fullerene, buckyball)
* C70 fullerene
* Cyanodecapentayne
* Cyanopentaacetylene
* Cyanotetra-acetylene
* Ethylene glycol
* Ethyl formate
* Methyl acetate
* Methyl-cyano-diacetylene
* Methyltriacetylene
* Propanal
* n-Propyl cyanide
* Pyrimidine
* Heptatrienyl radical

Deuterated
molecules|

* Ammonia
* Ammonium ion
* Formaldehyde
* Formyl radical
* Heavy water
* Hydrogen cyanide
* Hydrogen deuteride
* Hydrogen isocyanide
* Methylacetylene
* N2D+
* Trihydrogen cation

Unconfirmed|

* Anthracene
* Dihydroxyacetone
* Ethyl methyl ether
* Glycine
* Graphene
* Hemolithin (possibly 1st extraterrestrial protein found)
* H2NCO+
* Linear C5
* Naphthalene cation
* Phosphine
* Pyrene
* Silylidine

Related|

* Abiogenesis
* Astrobiology
* Astrochemistry
* Atomic and molecular astrophysics
* Chemical formula
* Circumstellar dust
* Circumstellar envelope
* Cosmic dust
* Cosmic ray
* Cosmochemistry
* Diffuse interstellar band
* Earliest known life forms
* Extraterrestrial life
* Extraterrestrial liquid water
* Forbidden mechanism
* Homochirality
* Intergalactic dust
* Interplanetary medium
* Interstellar medium
* Photodissociation region
* Iron–sulfur world theory
* Kerogen
* Molecules in stars
* Nexus for Exoplanet System Science
* Organic compound
* Outer space
* PAH world hypothesis
* Pseudo-panspermia
* Polycyclic aromatic hydrocarbon (PAH)
* RNA world hypothesis
* Spectroscopy
* Tholin

* Category:Astrochemistry
* Outer space portal
* Astronomy portal
* Chemistry portal

* v
* t
* e

Purine receptor modulators

Receptor
(ligands)|

| P0 (adenine)|

* Agonists: 8-Aminoadenine
* Adenine

|

(adenosine)|

* Agonists: 2-(1-Hexynyl)-N-methyladenosine
* 2-Cl-IB-MECA
* 2'-MeCCPA
* 4'-O-β-D-Glucosyl-9-O-(6''-deoxysaccharosyl)olivil
* 5'-N-ethylcarboxamidoadenosine
* Adenosine
* ADP
* AMP
* Apadenoson
* ATL-146e
* ATP
* BAY 60–6583
* Binodenoson
* Capadenoson
* CCPA
* CGS-21680
* CP-532,903
* Evodenoson
* GR 79236
* LUF-5835
* LUF-5845
* N6-Cyclopentyladenosine
* Namodenoson
* Neladenoson dalanate
* Piclidenoson
* Regadenoson
* SDZ WAG 994
* Selodenoson
* Sonedenoson
* Tecadenoson
* UK-432,097

* Antagonists: 7-Methylxanthine
* 8-Chlorotheophylline
* 8-Phenyl-1,3-dipropylxanthine
* 8-Phenyltheophylline
* Acefylline
* Aminophylline
* ATL-444
* Bamifylline
* Cafedrine
* Caffeine
* Caffeine citrate
* Cartazolate
* CGH-2466
* CGS-15943
* Choline theophyllinate
* Ciforadenant
* CPX
* CVT-6883
* Dimethazan
* DMPX
* DPCPX
* Dyphylline
* Enprofylline
* Etazolate
* Fenethylline
* IBMX
* Isovaleric acid
* Istradefylline
* KF-26777
* MRE3008F20
* MRS-1220
* MRS-1334
* MRS-1706
* MRS-1754
* MRS-3777
* Paraxanthine
* Pentoxifylline
* Preladenant
* Propentofylline
* Proxyphylline
* PSB-10
* PSB-11
* PSB-36
* PSB-603
* PSB-788
* PSB-1115
* Reversine
* Rolofylline
* SCH-442,416
* SCH-58261
* Theacrine
* Theobromine
* Theodrenaline
* Theophylline
* Tozadenant
* Tracazolate
* VUF-5574
* ZM-241,385

(nucleotide)|

| P2X
(ATPTooltip Adenosine triphosphate)|

* Agonists: 2-Me-SATP
* α,β-Me-ATP
* Adenosine
* ADP
* AMP
* Ap4A
* Ap5A
* ATP
* ATPγS
* BzATP
* Cibacron blue
* CTP
* D-β,γ-Me-ATP
* GTP
* HT-AMP
* Ivermectin
* L-β,γ-Me-ATP
* MRS-2219
* PAPET-ATP
* UTP
* Zinc

* Antagonists: 5-BDBD
* A-317491
* A-438079
* A-740003
* A-804598
* A-839977
* AF-353
* AZ-10606120
* AZ-11645373
* BBG
* Calcium
* Calmidazolium
* Chelerythrine
* Copper
* Emodin (Rheum officinale)
* Evans blue
* Gefapixant
* GW-791343
* HMA
* Ip5I
* isoPPADS
* JNJ-47965567
* KN-04
* KN-62
* Magnesium
* MRS-2159
* NF-023
* NF-110
* NF-157
* NF-279
* NF-449
* Opiranserin (VVZ-149)
* Oxidized-ATP
* Phenol Red
* Phenolphthalein
* PPADS
* PPNDS
* PSB-12062
* Puerarin (Radix puerariae)
* Purotoxin 1
* RB-2
* Ro 0437626
* Ro 51
* RO-3
* Sodium ferulate (Angelica sinensis, Ligusticum wallichii)
* Suramin
* TC-P 262
* Tetramethylpyrazine (ligustrazine) (Ligusticum wallichii)
* TNP-ATP
* Zinc

|

P2Y|

* Agonists: 2-Me-SADP
* 2-Me-SATP
* 2-Thio-UTP
* 5-Br-UDP
* 5-OMe-UDP
* α,β-Me-ATP
* Adenosine
* ADP
* ADPβS
* Ap3A
* AR-C 67085MX
* ATP
* ATPγS
* CTP
* dATP
* Denufosol
* Diquafosol
* IDP
* ITP
* INS-365
* INS-37217
* MRS-2365
* MRS-2690
* MRS-2693
* MRS-2768
* MRS-2957
* MRS-4062
* NF-546
* PAPET-ATP
* PSB-0474
* PSB-1114
* UDP
* UDPβS
* UDP-galactose
* UDP-glucose
* UDP-N-acetylglucosamine
* Up3U
* UTP
* UTPγS

* Antagonists: 2-Me-SAMP
* A3P5PS
* AMPαS
* Ap4A
* AR-C 66096
* AR-C 67085MX
* AR-C 69931MX
* AR-C 118925XX
* ATP
* BzATP
* C1330-7
* Cangrelor
* Clopidogrel
* Elinogrel
* Ip5I
* MRS-2179
* MRS-2211
* MRS-2279
* MRS-2395
* MRS-2500
* MRS-2578
* NF-157
* NF-340
* PIT
* PPADS
* Prasugrel
* PSB-0739
* RB-2
* Regrelor
* Suramin
* Ticagrelor
* Ticlopidine
* UDP

Transporter
(blockers)|

| CNTsTooltip Concentrative nucleoside transporters|

* 6-Hydroxy-7-methoxyflavone
* Adenosine
* dMeThPmR
* Estradiol
* KGO-2142
* KGO-2173
* MeThPmR
* Phloridzin
* Progesterone

|

ENTsTooltip Equilibrative nucleoside transporters|

* Barbiturates
* Benzodiazepines
* Cilostazol
* Dilazep
* Dipyridamole
* Estradiol
* Ethanol
* Hexobendine
* NBMPR
* Pentoxifylline
* Progesterone
* Propentofylline

PMATTooltip Plasma membrane monoamine transporter|

* Decynium-22

Enzyme
(inhibitors)|

| XOTooltip Xanthine oxidase|

* Allopurinol
* Amflutizole
* Benzbromarone
* Caffeic acid
* Cinnamaldehyde
* Cinnamomum osmophloeum
* Febuxostat
* Myo-inositol
* Kaempferol
* Myricetin
* Niraxostat
* Oxipurinol
* Phytic acid
* Pistacia integerrima
* Propolis
* Quercetin
* Tisopurine
* Topiroxostat

|

Others|

* Aminopterin
* Azathioprine
* Methotrexate
* Mycophenolic acid
* Pemetrexed
* Pralatrexate
* Many others

Others|

* Precursors: Adenine
* Adenosine
* AMP
* ADP
* ATP
* Cytosine
* Cytidine
* CMP
* CDP
* CTP
* Guanine
* Guanosine
* GMP
* GDP
* GTP
* Hypoxanthine
* Inosine
* IMP
* IDP
* ITP
* Ribose
* Uracil
* Uridine
* UMP
* UDP
* UTP

* Others: Chrysophanol (rhubarb)

See also: Receptor/signaling modulators

* v
* t
* e

Simple aromatic rings

1 ring|

| Three-membered|

* Borirene
* Cyclopropenone

|

Five-membered|

* Furan
* Pyrrole
* Imidazole
* Thiophene
* Phosphole
* Pyrazole
* Oxazole
* Isoxazole
* Thiazole
* Isothiazole
* Triazole
* Tetrazole
* Pentazole

Six-membered|

* Benzene
* Pyridine
* Pyrazine
* Pyrimidine
* Pyridazine
* Triazine
* Tetrazine
* Pentazine
* Hexazine

Seven-membered|

* Borepin
* Tropone

Nine-membered|

* Azonine

18-membered|

* Cyclooctadecanonaene

2 rings|

| Five + Five|

* Diazapentalene
* Thienothiophene
* Trithiapentalene

|

Five + Six|

* Benzofuran
* Isobenzofuran
* Indole
* Isoindole
* Benzothiophene
* Benzo(c)thiophene
* Benzophosphole
* Benzimidazole
* Purine
* Indazole
* Benzoxazole
* Benzisoxazole
* Benzothiazole
* 5-Aza-7-deazapurine

Six + Six|

* Naphthalene
* Quinoline
* Isoquinoline
* Quinoxaline
* Quinazoline
* Cinnoline
* Phthalazine

Five + Seven|

* Azulene

Authority control databases: National |

* Spain
* Germany
* Israel
* United States
* Japan

|

*[CID]: Compound ID
*[EPA]: U.S. Environmental Protection Agency
*[v]: View this template
*[t]: Discuss this template
*[e]: Edit this template
*[ATP]: Adenosine triphosphate
*[CNTs]: Concentrative nucleoside transporters
*[ENTs]: Equilibrative nucleoside transporters
*[PMAT]: Plasma membrane monoamine transporter
*[XO]: Xanthine oxidase