Molecular formula
C18H21N5O2
300 compounds have this formula on CompoundList.
- Molar mass
- 339.40g/mol
- Monoisotopic mass
- 343.1917Da
- Atoms
- 46
- Elements
- 4
- Rings plus double bonds
- 11
The formula C18H21N5O2 describes a molecule made of 18 carbon atoms, 21 hydrogen atoms, 5 nitrogen atoms and 2 oxygen atoms. It is written in Hill notation: carbon first, then hydrogen, then the other elements in alphabetical order. The formula tells you which atoms are present, not how they are connected, which is why several different chemicals can share it.
Elemental composition
- C Carbon × 1863.70%12.011 × 18 = 216.198 g/mol
- H Hydrogen × 216.24%1.008 × 21 = 21.168 g/mol
- N Nitrogen × 520.64%14.007 × 5 = 70.035 g/mol
- O Oxygen × 29.43%15.999 × 2 = 31.998 g/mol
Look up another formula
Compounds with the formula C18H21N5O2
Isomers we list, best known first. Open one to see its structure, properties, safety data and suppliers.
Showing 1 to 100 of 300 compounds
Alogliptin
CAS 850649-61-5C18H21N5O2
7-Allyl-1,3-dimethyl-8-(phenethylamino)-1H-purine-2,6(3H,7H)-dione
CAS 378208-99-2C18H21N5O2
7-Benzyl-8-(cyclopentylamino)-3-methyl-1H-purine-2,6(3H,7H)-dione
CAS 578752-07-5C18H21N5O2
![1-sec-Butyl-N-ethyl-2-imino-5-oxo-1,5-dihydro-2H-dipyrido[1,2-A:2,3-D]pyrimidine-3-carboxamide chemical structure, C18H21N5O2, CAS 510733-35-4](/s/OXMBTESBNUPFFA-UHFFFAOYSA-N.svg)
1-sec-Butyl-N-ethyl-2-imino-5-oxo-1,5-dihydro-2H-dipyrido[1,2-A:2,3-D]pyrimidine-3-carboxamide
CAS 510733-35-4C18H21N5O2
![N-Ethyl-2-imino-10-methyl-5-oxo-1-propyl-1,5-dihydro-2H-dipyrido[1,2-A:2,3-D]pyrimidine-3-carboxamide chemical structure, C18H21N5O2, CAS 371210-68-3](/s/DRCIAVLYIGHEAD-UHFFFAOYSA-N.svg)
N-Ethyl-2-imino-10-methyl-5-oxo-1-propyl-1,5-dihydro-2H-dipyrido[1,2-A:2,3-D]pyrimidine-3-carboxamide
CAS 371210-68-3C18H21N5O2
![9-(4-Ethylphenyl)-1,7-dimethyl-7,8-dihydro-6H-purino[7,8-a]pyrimidine-2,4-dione chemical structure, C18H21N5O2, CAS 714924-08-0](/s/YUCWMIHQRZZBGD-UHFFFAOYSA-N.svg)
9-(4-Ethylphenyl)-1,7-dimethyl-7,8-dihydro-6H-purino[7,8-a]pyrimidine-2,4-dione
CAS 714924-08-0C18H21N5O2
![9-(3,5-Dimethylphenyl)-1,7-dimethyl-7,8-dihydro-6H-purino[7,8-a]pyrimidine-2,4-dione chemical structure, C18H21N5O2, CAS 714245-09-7](/s/IPELEGBBNWXWNG-UHFFFAOYSA-N.svg)
9-(3,5-Dimethylphenyl)-1,7-dimethyl-7,8-dihydro-6H-purino[7,8-a]pyrimidine-2,4-dione
CAS 714245-09-7C18H21N5O2
![2-(1-tert-Butyl-4-oxopyrazolo[3,4-d]pyrimidin-5-yl)-N-(4-methylphenyl)acetamide chemical structure, C18H21N5O2, CAS 863447-66-9](/s/LLDHFCMHBWIXND-UHFFFAOYSA-N.svg)
2-(1-tert-Butyl-4-oxopyrazolo[3,4-d]pyrimidin-5-yl)-N-(4-methylphenyl)acetamide
CAS 863447-66-9C18H21N5O2
![9-(3,4-Dimethylphenyl)-1,7-dimethyl-7,8-dihydro-6H-purino[7,8-a]pyrimidine-2,4-dione chemical structure, C18H21N5O2, CAS 714949-70-9](/s/VOUGOJOGDHGGMU-UHFFFAOYSA-N.svg)
9-(3,4-Dimethylphenyl)-1,7-dimethyl-7,8-dihydro-6H-purino[7,8-a]pyrimidine-2,4-dione
CAS 714949-70-9C18H21N5O2
![1,7-Dimethyl-9-(2-phenylethyl)-1,3,5-trihydro-6H,7H,8H-1,3-diazaperhydroino[1, 2-h]purine-2,4-dione chemical structure, C18H21N5O2, CAS 714241-66-4](/s/NVJPEGACVLJJSJ-UHFFFAOYSA-N.svg)
1,7-Dimethyl-9-(2-phenylethyl)-1,3,5-trihydro-6H,7H,8H-1,3-diazaperhydroino[1, 2-h]purine-2,4-dione
CAS 714241-66-4C18H21N5O2
![N-Benzyl-2-(1-(tert-butyl)-4-oxo-1H-pyrazolo[3,4-d]pyrimidin-5(4H)-yl)acetamide chemical structure, C18H21N5O2, CAS 863448-06-0](/s/ARDBTQKGFYXLIS-UHFFFAOYSA-N.svg)
N-Benzyl-2-(1-(tert-butyl)-4-oxo-1H-pyrazolo[3,4-d]pyrimidin-5(4H)-yl)acetamide
CAS 863448-06-0C18H21N5O2
![2,4-Diamino-6-[N-(2',5'-dimethoxybenzyl)-N-methylamino]quinazoline chemical structure, C18H21N5O2, CAS 213338-96-6](/s/YBJANOUTWRTBDK-UHFFFAOYSA-N.svg)
2,4-Diamino-6-[N-(2',5'-dimethoxybenzyl)-N-methylamino]quinazoline
CAS 213338-96-6C18H21N5O2
7-Benzyl-3-methyl-8-piperidin-1-ylpurine-2,6-dione
CAS 106306-87-0C18H21N5O2
8-Allylamino-3-methyl-7-(3-phenyl-propyl)-3,7-dihydro-purine-2,6-dione
CAS 377052-96-5C18H21N5O2
2-((6-(3-Amino-1-piperidinyl)-3,4-dihydro-3-methyl-2,4-dioxo-1(2H)-pyrimidinyl)methyl)benzonitrile
CAS 865759-26-8C18H21N5O2
![3-Ethyl-1-methyl-9-(3-methylphenyl)-7,8-dihydro-6H-purino[7,8-a]pyrimidine-2,4-dione chemical structure, C18H21N5O2, CAS 844646-26-0](/s/NOCBBKPMQOKZCI-UHFFFAOYSA-N.svg)
3-Ethyl-1-methyl-9-(3-methylphenyl)-7,8-dihydro-6H-purino[7,8-a]pyrimidine-2,4-dione
CAS 844646-26-0C18H21N5O2
![9-Benzyl-3-ethyl-1-methyl-7,8-dihydro-6H-purino[7,8-a]pyrimidine-2,4-dione chemical structure, C18H21N5O2, CAS 877622-32-7](/s/RRFCOEBECDVRRA-UHFFFAOYSA-N.svg)
9-Benzyl-3-ethyl-1-methyl-7,8-dihydro-6H-purino[7,8-a]pyrimidine-2,4-dione
CAS 877622-32-7C18H21N5O2
![2-[(6-Ethoxy-4-methylquinazolin-2-yl)amino]-5-ethyl-6-methylpyrimidin-4(1H)-one chemical structure, C18H21N5O2, CAS 511515-23-4](/s/FMOZQMQXFOCIFQ-UHFFFAOYSA-N.svg)
2-[(6-Ethoxy-4-methylquinazolin-2-yl)amino]-5-ethyl-6-methylpyrimidin-4(1H)-one
CAS 511515-23-4C18H21N5O2
![1-Methyl-8-(4-methylphenyl)-3-propyl-7,8-dihydro-1H-imidazo[2,1-f]purine-2,4(3H,6H)-dione chemical structure, C18H21N5O2, CAS 300703-05-3](/s/JUGSNMRURXIPBK-UHFFFAOYSA-N.svg)
1-Methyl-8-(4-methylphenyl)-3-propyl-7,8-dihydro-1H-imidazo[2,1-f]purine-2,4(3H,6H)-dione
CAS 300703-05-3C18H21N5O2
8-(Benzylamino)-3-methyl-7-(3-methylbut-2-en-1-yl)-1H-purine-2,6(3H,7H)-dione
CAS 313470-64-3C18H21N5O2
![N-(6-Benzyl-5-methyl-7-oxo-4,7-dihydro[1,2,4]triazolo[1,5-a]pyrimidin-2-yl)-3-methylbutanamide chemical structure, C18H21N5O2, CAS 879072-99-8](/s/YSEKIUZDKURAMX-UHFFFAOYSA-N.svg)
N-(6-Benzyl-5-methyl-7-oxo-4,7-dihydro[1,2,4]triazolo[1,5-a]pyrimidin-2-yl)-3-methylbutanamide
CAS 879072-99-8C18H21N5O2
Carbamic acid, (5-amino-3-(3,4-dimethylphenyl)-1,2-dihydropyrido(3,4-b)pyrazin-7-yl)-, ethyl ester
CAS 82585-94-2C18H21N5O2
Ethyl (5-amino-3-(2,4-dimethylphenyl)-1,2-dihydropyrido(3,4-b)pyrazin-7-yl)carbamate
CAS 82585-93-1C18H21N5O2
8-(Benzyl(methyl)amino)-3-methyl-7-(2-methylallyl)-1H-purine-2,6(3H,7H)-dione
CAS 376378-79-9C18H21N5O2
- Ret-IN-32414374-53-9C18H21N5O2
- 1-(4-(2-(1H-Pyrazol-1-yl)ethyl)piperazin-1-yl)-2-(benzo[d]isoxazol-3-yl)ethanone1334375-15-3C18H21N5O2
- Ethyl N-(5-amino-2-ethyl-3-phenyl-1,2-dihydropyrido[3,4-b]pyrazin-7-yl)carbamate135696-47-8C18H21N5O2
- N1-phenyl-N2-((1-(pyrimidin-2-yl)piperidin-4-yl)methyl)oxalamide1234897-26-7C18H21N5O2
- Carbamic acid, (5-amino-1,2-dihydro-3-(2-phenylethyl)pyrido(3,4-b)pyrazin-7-yl)-, ethyl ester83269-05-0C18H21N5O2
- N-[2-(4-Methoxy-1H-indol-1-yl)ethyl]-3-(2-pyrimidinylamino)propanamide1435980-67-8C18H21N5O2
- 1-Isopropyl-5-methyl-N-(5-(4-methylbenzyl)-1,3,4-oxadiazol-2-yl)-1H-pyrazole-3-carboxamide1171054-12-8C18H21N5O2
- N-{3-Ethoxy-4-[(4-methylbenzyl)oxy]benzyl}-N-(2H-tetraazol-5-yl)amine879071-48-4C18H21N5O2
- N-(2-(5-Benzyl-4-oxo-4,5-dihydro-1H-pyrazolo[3,4-d]pyrimidin-1-yl)ethyl)isobutyramide922055-45-6C18H21N5O2
- N-(2-(5-(2-Methylbenzyl)-4-oxo-4,5-dihydro-1H-pyrazolo[3,4-d]pyrimidin-1-yl)ethyl)propionamide922116-99-2C18H21N5O2
- N-[4-Oxo-3-(propan-2-yl)-3,4-dihydroquinazolin-6-yl]-4-(1H-pyrazol-1-yl)butanamide1574325-81-7C18H21N5O2
- 4-(1-Methylethoxy)-2-(4-morpholinyl)-8-(1H-pyrazol-3-yl)-1,7-naphthyridine1876467-01-4C18H21N5O2
- N-(5-(1,5-Dimethyl-1H-pyrazol-3-yl)-1,3,4-oxadiazol-2-yl)-2-(4-isopropylphenyl)acetamide1020453-46-6C18H21N5O2
- 1-{[(1-Cyano-1,2-dimethylpropyl)carbamoyl]methyl}-3-phenyl-1H-pyrazole-4-carboxamide1311976-61-0C18H21N5O2
- 7-Benzyl-1,3-dimethyl-8-(pyrrolidin-1-yl)-1H-purine-2,6(3H,7H)-dione361174-76-7C18H21N5O2
- 4-(Dimethylaminodiazenyl)-N-[(E)-(4-ethoxyphenyl)methylideneamino]benzamide62591-55-3C18H21N5O2
- 4-(6-Methoxy-[1,2,4]triazolo[4,3-b]pyridazin-3-yl)-N-phenethylbutanamide1374541-01-1C18H21N5O2
- 8-[Benzyl(methyl)amino]-1,3-dimethyl-7-(prop-2-en-1-yl)-2,3,6,7-tetrahydro-1H-purine-2,6-dione377052-13-6C18H21N5O2
- 3-Methyl-8-[(4-methylphenyl)methylamino]-7-(2-methylprop-2-enyl)purine-2,6-dione332099-00-0C18H21N5O2
- 3-Methyl-7-(3-methylbenzyl)-8-(pyrrolidin-1-yl)-1H-purine-2,6(3H,7H)-dione361174-73-4C18H21N5O2
- 8-(Benzylamino)-1,3-dimethyl-7-(2-methylprop-2-enyl)purine-2,6-dione377053-14-0C18H21N5O2
- 1,3-Dimethyl-10-(4-methylphenyl)-6,7,8,9-tetrahydropurino[7,8-a][1,3]diazepine-2,4-dione487007-04-5C18H21N5O2
- Alogliptin-13Cd31246817-18-4C18H21N5O2
- 4-(3-Hydroxyphenyl)-8-methyl-2-piperidin-1-yl-1,4-dihydro-6H-pyrimido[1,2-a][1,3,5]triazin-6-one925143-92-6C18H21N5O2
- 1,9-Dimethyl-2-(4-methylpiperazine-1-carbonyl)pyrido[1,2-a]pyrrolo[2,3-d]pyrimidin-4(1H)-one864854-69-3C18H21N5O2
- 2-((8-Methoxy-4-methylquinazolin-2-yl)amino)-6-methyl-5-propylpyrimidin-4(3H)-one903468-04-2C18H21N5O2
- 1-Methyl-9-phenyl-3-propyl-7,8-dihydro-6H-purino[7,8-a]pyrimidine-2,4-dione332400-72-3C18H21N5O2
- N-Ethyl-6-imino-13-methyl-2-oxo-7-propyl-1,7,9-triazatricyclo[8.4.0.0^{3,8}]tetradeca-3(8),4,9,11,13-pentaene-5-carboxamide842962-86-1C18H21N5O2
- 3-Ethyl-8-(4-ethylphenyl)-1-methyl-7,8-dihydro-1H-imidazo[2,1-f]purine-2,4(3H,6H)-dione872840-42-1C18H21N5O2
- 1-Hexyl-2-imino-5-oxo-1,5-dihydro-2H-dipyrido[1,2-a:2,3-d]pyrimidine-3-carboxamide608106-04-3C18H21N5O2
- 8-(Allylamino)-1,3-dimethyl-7-(4-methylbenzyl)-1H-purine-2,6(3H,7H)-dione375355-28-5C18H21N5O2
- 8-(4-Butylphenyl)-1-methyl-1,3,5-trihydroimidazolidino[1,2-h]purine-2,4-dione879457-67-7C18H21N5O2
- 1-Cyclopentyl-6-(1-ethyl-1H-pyrazol-3-yl)-3-methyl-1H-pyrazolo[3,4-b]pyridine-4-carboxylic acid1170560-04-9C18H21N5O2
- 3-Ethyl-1-methyl-9-(4-methylphenyl)-7,8-dihydro-6H-purino[7,8-a]pyrimidine-2,4-dione844653-73-2C18H21N5O2
- N-Ethyl-6-imino-11-methyl-2-oxo-7-(propan-2-yl)-1,7,9-triazatricyclo[8.4.0.0^{3,8}]tetradeca-3(8),4,9,11,13-pentaene-5-carboxamide799251-04-0C18H21N5O2
- 4-(2,6-Dimethylmorpholin-4-yl)-1-(4-methoxyphenyl)-1H-pyrazolo[3,4-d]pyrimidine393822-76-9C18H21N5O2
- [5-Methyl-7-(4-methylphenyl)-3,7-dihydro[1,2,4]triazolo[1,5-a]pyrimidin-6-yl](morpholin-4-yl)methanone919735-45-8C18H21N5O2
- 4-(4-Hydroxyphenyl)-8-methyl-2-(piperidin-1-yl)-1,4-dihydro-6H-pyrimido[1,2-a][1,3,5]triazin-6-one925626-25-1C18H21N5O2
- 9-(3,5-Dimethylphenyl)-1,3-dimethyl-6,7,8,9-tetrahydropyrimido[2,1-f]purine-2,4(1H,3H)-dione847246-35-9C18H21N5O2
- 1-(4-Butylphenyl)-5-methyl-N-(5-methyl-1,2-oxazol-3-yl)-1H-1,2,3-triazole-4-carboxamide915930-50-6C18H21N5O2
- Cyclopropyl(4-(5-(5-cyclopropyl-1,2,4-oxadiazol-3-yl)pyridin-2-yl)piperazin-1-yl)methanone1219904-10-5C18H21N5O2
- Alogliptin-d31133421-35-8C18H21N5O2
- 2-[[3,4-Dihydro-3-methyl-2,4-dioxo-6-[(3R)-3-piperidinylamino]-1(2H)-pyrimidinyl]methyl]-benzonitrile2089611-85-6C18H21N5O2
- 2-((4-(2-(Pyrrolidin-1-yl)ethoxy)phenyl)amino)-3H-pyrrolo[2,3-d]pyrimidin-4(7H)-one1142945-82-1C18H21N5O2
- N-Ethyl-6-imino-13-methyl-2-oxo-7-(propan-2-yl)-1,7,9-triazatricyclo[8.4.0.0^{3,8}]tetradeca-3(8),4,9,11,13-pentaene-5-carboxamide799251-05-1C18H21N5O2
- 6-(3,4-Dimethylphenyl)-2-ethyl-4-methyl-7,8-dihydropurino[7,8-a]imidazole-1,3-dione872842-84-7C18H21N5O2
- 4-Methyl-6-(2-methylphenyl)-2-propyl-7,8-dihydropurino[7,8-a]imidazole-1,3-dione893962-50-0C18H21N5O2
- 1,3,7-Trimethyl-9-(4-methylphenyl)-7,8-dihydro-6H-purino[7,8-a]pyrimidine-2,4-dione848919-62-0C18H21N5O2
- 1-Methyl-8-(3-methylphenyl)-3-propyl-1H,2H,3H,4H,6H,7H,8H-imidazo[1,2-g]purine-2,4-dione872839-89-9C18H21N5O2
- N-[(Z)-1-[4-(Cyclobutanecarbonylamino)phenyl]ethylideneamino]-1-methylpyrazole-3-carboxamide490014-39-6C18H21N5O2
- 1,4-Di(4-morpholinyl)-5H-pyridazino[4,5-b]indole80985-57-5C18H21N5O2
- 1-Benzyl-3,7-dimethyl-8-(pyrrolidin-1-yl)-1H-purine-2,6(3H,7H)-dione876893-79-7C18H21N5O2
- 9-(2,4-Dimethylphenyl)-1,3-dimethyl-6,7,8,9-tetrahydropyrimido[2,1-f]purine-2,4(1H,3H)-dione923399-58-0C18H21N5O2
- 9-(2,3-Dimethylphenyl)-1,3-dimethyl-6,7,8,9-tetrahydropyrimido[2,1-f]purine-2,4(1H,3H)-dione923481-41-8C18H21N5O2
- 2-({3-[(1-Phenyl-1H-tetrazol-5-yl)oxy]benzyl}amino)butan-1-ol932214-71-6C18H21N5O2
- N-{3-Ethoxy-4-[(1-phenyl-1H-tetrazol-5-yl)oxy]benzyl}ethanamine932175-38-7C18H21N5O2
- N-{3-Methoxy-4-[(1-phenyl-1H-tetrazol-5-yl)oxy]benzyl}propan-2-amine932215-26-4C18H21N5O2
- 4-tert-Butyl-N-[5-(1,5-dimethyl-1H-pyrazol-3-yl)-1,3,4-oxadiazol-2-yl]benzamide1019101-78-0C18H21N5O2
- (1H-Benzo[d]imidazol-5-yl)(4-(5-isopropyl-1,3,4-oxadiazol-2-yl)piperidin-1-yl)methanone1210883-71-8C18H21N5O2
- N-(2,5-Dimethoxybenzyl)-4-(3,5-dimethyl-1H-pyrazol-1-yl)pyrimidin-2-amine1251680-39-3C18H21N5O2
- N-[(3,4-Dimethoxyphenyl)methyl]-4-(3,5-dimethyl-1H-pyrazol-1-yl)pyrimidin-2-amine1251632-87-7C18H21N5O2
- N-(2-((2-(3,5-Dimethyl-1H-pyrazol-1-yl)ethyl)amino)-2-oxoethyl)-1H-indole-3-carboxamide1251696-52-2C18H21N5O2
- 1-(4-(2-(1H-Imidazol-1-yl)ethyl)piperazin-1-yl)-2-(benzo[d]isoxazol-3-yl)ethanone1396793-51-3C18H21N5O2
- 3-Methoxy-1-methyl-N-(3-(2-phenyl-1H-imidazol-1-yl)propyl)-1H-pyrazole-4-carboxamide1421467-98-2C18H21N5O2
- 3-(3,5-Dimethylisoxazol-4-yl)-1-(2-methyl-8,9-dihydropyrazolo[1,5-a]pyrido[3,4-e]pyrimidin-7(6H)-yl)propan-1-one1706220-27-0C18H21N5O2
- 5-Propyl-2-[(4,6,7-trimethylquinazolin-2-yl)amino]pyrimidine-4,6-diol352660-34-5C18H21N5O2
- 9-(4-Ethylphenyl)-1,3-dimethyl-7,8-dihydro-6H-purino[7,8-a]pyrimidine-2,4-dione848736-60-7C18H21N5O2
- N-(6,7-Dihydro-5H-cyclopenta[D][1,2,4]triazolo[1,5-A]pyrimidin-8-yl)-N-(3,4-dimethoxyphenethyl)amine626216-40-8C18H21N5O2
- 1H-Benzotriazole, 1-(cyclohexylcarbonyl)-5-(1,4,5,6-tetrahydro-4-methyl-6-oxo-3-pyridazinyl)-85634-51-1C18H21N5O2
- 3-Ethyl-1,7-dimethyl-9-phenyl-7,8-dihydro-6H-purino[7,8-a]pyrimidine-2,4-dione843669-33-0C18H21N5O2
- 6-(3,5-Dimethylphenyl)-2-ethyl-4-methyl-7,8-dihydropurino[7,8-a]imidazole-1,3-dione872843-14-6C18H21N5O2
- N-[(3-Ethoxy-2-phenylmethoxyphenyl)methyl]-1-methyltetrazol-5-amine878425-65-1C18H21N5O2
- 5H-Pyridazino(3,4-b)(1,4)benzoxazine, 7-acetyl-10-methyl-2-(4-methylpiperazin-1-yl)-62637-15-4C18H21N5O2
- 2-(1-(tert-Butyl)-4-oxo-1H-pyrazolo[3,4-d]pyrimidin-5(4H)-yl)-N-(m-tolyl)acetamide863447-65-8C18H21N5O2
- 2-Methyl-2-({3-[(1-phenyl-1H-tetrazol-5-yl)oxy]benzyl}amino)propan-1-ol932155-15-2C18H21N5O2
- 1H-Imidazo[2,1-f]purine-2,4(3H,6H)-dione, 7,8-dihydro-1-methyl-8-(phenylmethyl)-3-propyl-872838-47-6C18H21N5O2
Frequently asked questions
What is the molar mass of C18H21N5O2?
The molar mass of C18H21N5O2 is 339.40 g/mol, calculated from standard atomic weights for 18 carbon atoms, 21 hydrogen atoms, 5 nitrogen atoms and 2 oxygen atoms. The monoisotopic mass is 343.1917 Da.
How many compounds have the formula C18H21N5O2?
CompoundList lists 300 compounds with the molecular formula C18H21N5O2, including Alogliptin, 7-Allyl-1,3-dimethyl-8-(phenethylamino)-1H-purine-2,6(3H,7H)-dione, 7-Benzyl-8-(cyclopentylamino)-3-methyl-1H-purine-2,6(3H,7H)-dione. Compounds that share a formula are isomers. They contain the same atoms arranged differently, so their properties, uses and prices can be very different.
What is the degree of unsaturation of C18H21N5O2?
C18H21N5O2 has a degree of unsaturation of 11. That is the total number of rings and pi bonds (a double bond counts as one, a triple bond as two) in any structure with this formula.