Molecular formula
C21H23N3O5
165 compounds have this formula on CompoundList.
- Molar mass
- 397.43g/mol
- Monoisotopic mass
- 397.1638Da
- Atoms
- 52
- Elements
- 4
- Rings plus double bonds
- 12
The formula C21H23N3O5 describes a molecule made of 21 carbon atoms, 23 hydrogen atoms, 3 nitrogen atoms and 5 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 × 2163.47%12.011 × 21 = 252.231 g/mol
- H Hydrogen × 235.83%1.008 × 23 = 23.184 g/mol
- N Nitrogen × 310.57%14.007 × 3 = 42.021 g/mol
- O Oxygen × 520.13%15.999 × 5 = 79.995 g/mol
Look up another formula
Compounds with the formula C21H23N3O5
Isomers we list, best known first. Open one to see its structure, properties, safety data and suppliers.
Showing 1 to 100 of 165 compounds
Strychnidin-10-one, nitrate (1:1)
CAS 66-32-0C21H23N3O5
Abexinostat
CAS 783355-60-2C21H23N3O5
Navarixin anhydrous
CAS 473727-83-2C21H23N3O5
Fmoc-L-citrulline
CAS 133174-15-9C21H23N3O5
![3-[(4-Methoxyphenyl)methyl]-N-(3-methoxypropyl)-2,4-dioxo-1H-quinazoline-7-carboxamide chemical structure, C21H23N3O5, CAS 892275-25-1](/s/YPIIMFTYFCSQLC-UHFFFAOYSA-N.svg)
3-[(4-Methoxyphenyl)methyl]-N-(3-methoxypropyl)-2,4-dioxo-1H-quinazoline-7-carboxamide
CAS 892275-25-1C21H23N3O5
4-((3,4-Dimethoxyphenethyl)amino)-1-ethyl-3-nitroquinolin-2(1H)-one
CAS 433309-56-9C21H23N3O5
Piperaline fumarate
CAS 39640-14-7C21H23N3O5
![(2R)-5-(Carbamoylamino)-2-({[(9H-fluoren-9-yl)methoxy]carbonyl}amino)pentanoic acid chemical structure, C21H23N3O5, CAS 200344-33-8](/s/NBMSMZSRTIOFOK-GOSISDBHSA-N.svg)
(2R)-5-(Carbamoylamino)-2-({[(9H-fluoren-9-yl)methoxy]carbonyl}amino)pentanoic acid
CAS 200344-33-8C21H23N3O5
Diethyl 4-oxo-2,6-di(pyridin-3-yl)piperidine-3,5-dicarboxylate
CAS 94918-93-1C21H23N3O5
![7-Diethylamino-3-[N-(3-maleimidopropyl)carbamoyl]coumarin chemical structure, C21H23N3O5, CAS 160291-54-3](/s/PHFIKYNYJRZPND-UHFFFAOYSA-N.svg)
7-Diethylamino-3-[N-(3-maleimidopropyl)carbamoyl]coumarin
CAS 160291-54-3C21H23N3O5
![2-(4-(Benzo[D]1,3-dioxolan-5-ylmethyl)piperazinyl)-N-benzo[D]1,3-dioxolen-5-ylethanamide chemical structure, C21H23N3O5, CAS 484027-76-1](/s/GJDBZWLJMRJILJ-UHFFFAOYSA-N.svg)
2-(4-(Benzo[D]1,3-dioxolan-5-ylmethyl)piperazinyl)-N-benzo[D]1,3-dioxolen-5-ylethanamide
CAS 484027-76-1C21H23N3O5
![Methyl 3-{[4-(2,3-dimethylphenyl)piperazinyl]carbonyl}-5-nitrobenzoate chemical structure, C21H23N3O5, CAS 349440-02-4](/s/XDUJOGYGXAOYKO-UHFFFAOYSA-N.svg)
Methyl 3-{[4-(2,3-dimethylphenyl)piperazinyl]carbonyl}-5-nitrobenzoate
CAS 349440-02-4C21H23N3O5
![1-(1-(2,3-Dihydrobenzo[b][1,4]dioxin-6-yl)-5-oxopyrrolidin-3-yl)-3-(2-methoxy-5-methylphenyl)urea chemical structure, C21H23N3O5, CAS 877641-08-2](/s/RMRZJAFKVAGMMT-UHFFFAOYSA-N.svg)
1-(1-(2,3-Dihydrobenzo[b][1,4]dioxin-6-yl)-5-oxopyrrolidin-3-yl)-3-(2-methoxy-5-methylphenyl)urea
CAS 877641-08-2C21H23N3O5
N-(1,5-Dimethyl-3-oxo-2-phenyl-2,3-dihydro-1H-pyrazol-4-yl)-3,4,5-trimethoxybenzamide
CAS 3553-11-5C21H23N3O5
![4-{[4-(Furan-2-ylcarbonyl)piperazin-1-yl]carbonyl}-1-(4-methoxyphenyl)pyrrolidin-2-one chemical structure, C21H23N3O5, CAS 878426-68-7](/s/JYMBOABAEFZDQH-UHFFFAOYSA-N.svg)
4-{[4-(Furan-2-ylcarbonyl)piperazin-1-yl]carbonyl}-1-(4-methoxyphenyl)pyrrolidin-2-one
CAS 878426-68-7C21H23N3O5
![1-[4-(1,3-Benzodioxol-5-ylmethyl)piperazin-1-yl]-2-(4-nitrophenyl)propan-1-one chemical structure, C21H23N3O5, CAS 694444-26-3](/s/BIFWVGRHMXQOFP-UHFFFAOYSA-N.svg)
1-[4-(1,3-Benzodioxol-5-ylmethyl)piperazin-1-yl]-2-(4-nitrophenyl)propan-1-one
CAS 694444-26-3C21H23N3O5
![Methyl 4-{4-[2-(4-methylphenyl)-2-oxoethyl]piperazino}-3-nitrobenzenecarboxylate chemical structure, C21H23N3O5, CAS 341967-74-6](/s/PGWBIOUVFWVCIT-UHFFFAOYSA-N.svg)
Methyl 4-{4-[2-(4-methylphenyl)-2-oxoethyl]piperazino}-3-nitrobenzenecarboxylate
CAS 341967-74-6C21H23N3O5
![N-(2,5-Dimethoxyphenyl)-2-[3-oxo-1-(phenylcarbonyl)piperazin-2-yl]acetamide chemical structure, C21H23N3O5, CAS 1008009-44-6](/s/OCWZYSARHPVMKC-UHFFFAOYSA-N.svg)
N-(2,5-Dimethoxyphenyl)-2-[3-oxo-1-(phenylcarbonyl)piperazin-2-yl]acetamide
CAS 1008009-44-6C21H23N3O5
![[2-(4-Morpholin-4-ylanilino)-2-oxoethyl] 4-acetamidobenzoate chemical structure, C21H23N3O5, CAS 721906-80-5](/s/ZRUSHSJCBMWWLH-UHFFFAOYSA-N.svg)
[2-(4-Morpholin-4-ylanilino)-2-oxoethyl] 4-acetamidobenzoate
CAS 721906-80-5C21H23N3O5
![Ethyl 5-{[(N-acetyltryptophyl)amino]methyl}-2-furoate chemical structure, C21H23N3O5, CAS 1008038-82-1](/s/AEIBIXZWLWWLAC-UHFFFAOYSA-N.svg)
Ethyl 5-{[(N-acetyltryptophyl)amino]methyl}-2-furoate
CAS 1008038-82-1C21H23N3O5
![N'-[2-(2,6-Dimethylphenoxy)acetyl]-4-(2-oxo-1,3-benzoxazol-3-yl)butanehydrazide chemical structure, C21H23N3O5, CAS 852913-07-6](/s/UVCXYXBPUOZQJQ-UHFFFAOYSA-N.svg)
N'-[2-(2,6-Dimethylphenoxy)acetyl]-4-(2-oxo-1,3-benzoxazol-3-yl)butanehydrazide
CAS 852913-07-6C21H23N3O5
4-(Furan-2-carbonyl)-3-hydroxy-1-(3-morpholinopropyl)-5-(pyridin-3-yl)-1H-pyrrol-2(5H)-one
CAS 380904-61-0C21H23N3O5
![4-[3-(3,4-Dimethoxyphenyl)-1,2,4-oxadiazol-5-yl]-N-(2-methoxyphenyl)butanamide chemical structure, C21H23N3O5, CAS 835899-85-9](/s/KBIPRURLRWOMBL-UHFFFAOYSA-N.svg)
4-[3-(3,4-Dimethoxyphenyl)-1,2,4-oxadiazol-5-yl]-N-(2-methoxyphenyl)butanamide
CAS 835899-85-9C21H23N3O5
![[(1-Cyanocyclohexyl)(methyl)carbamoyl]methyl 2-(1,3-dioxo-2,3-dihydro-1H-isoindol-2-yl)propanoate chemical structure, C21H23N3O5, CAS 875459-45-3](/s/LMMLOZLEZBXMCQ-UHFFFAOYSA-N.svg)
[(1-Cyanocyclohexyl)(methyl)carbamoyl]methyl 2-(1,3-dioxo-2,3-dihydro-1H-isoindol-2-yl)propanoate
CAS 875459-45-3C21H23N3O5
- N-(2-(2-(3-(Allyloxy)benzylidene)hydrazino)-2-oxoethyl)-3,4-dimethoxybenzamide767338-88-5C21H23N3O5
- N1-benzyl-N2-((3-(4-methoxybenzoyl)oxazolidin-2-yl)methyl)oxalamide874805-18-2C21H23N3O5
- Methyl 4-(2-(((4-propoxybenzoyl)amino)acetyl)carbohydrazonoyl)benzoate765907-73-1C21H23N3O5
- N-[2-(2H-1,3-Benzodioxol-5-yl)-2-(morpholin-4-yl)ethyl]-N'-phenylethanediamide887218-36-2C21H23N3O5
- 1-(3-Ethoxyphenyl)-3-[4-(furan-2-carbonyl)piperazin-1-yl]pyrrolidine-2,5-dione354540-10-6C21H23N3O5
- 1-Ethyl-7-methyl-4-oxo-N-(3,4,5-trimethoxyphenyl)-1,4-dihydro-1,8-naphthyridine-3-carboxamide403734-17-8C21H23N3O5
- 3-Hydroxy-4-(5-methylfuran-2-carbonyl)-1-(2-morpholinoethyl)-5-(pyridin-2-yl)-1H-pyrrol-2(5H)-one618877-74-0C21H23N3O5
- 2-(3,4-Dimethoxyphenyl)-N-{[3-(4-methoxyphenyl)-1,2,4-oxadiazol-5-yl]methyl}-N-methylacetamide887690-38-2C21H23N3O5
- Ethyl 4-(2-(3-(4-methoxyphenyl)-2-oxoimidazolidin-1-yl)acetamido)benzoate1327298-96-3C21H23N3O5
- N'-[2-(Furan-2-yl)-2-hydroxypropyl]-N-{3-methyl-2-oxo-1-azatricyclo[6.3.1.0^{4,12}]dodeca-4,6,8(12)-trien-6-yl}ethanediamide1421532-23-1C21H23N3O5
- N1-(4-methoxyphenyl)-N2-(2-oxo-2-(2-phenylmorpholino)ethyl)oxalamide953950-36-2C21H23N3O5
- N-{2-[(2H-1,3-benzodioxol-5-yl)formamido]ethyl}-4-(2-methylpropanamido)benzamide1040673-00-4C21H23N3O5
- Navarixin, (S)-473727-82-1C21H23N3O5
- N-[5-(3,4,5-Triethoxyphenyl)-1,3,4-oxadiazol-2-yl]benzamide20113-25-1C21H23N3O5
- 4-(3,4-Dimethoxyphenyl)-N-(4-methoxyphenyl)-6-methyl-2-oxo-1,2,3,4-tetrahydropyrimidine-5-carboxamide333431-90-6C21H23N3O5
- 4-(3,4-Dimethoxyphenyl)-N-(2-methoxyphenyl)-6-methyl-2-oxo-1,2,3,4-tetrahydropyrimidine-5-carboxamide421575-62-4C21H23N3O5
- N-(4-Ethoxyphenyl)-4-(4-hydroxy-3-methoxyphenyl)-6-methyl-2-oxo-3,4-dihydro-1H-pyrimidine-5-carboxamide380644-46-2C21H23N3O5
- N-(2,4-Dimethoxyphenyl)-4-(3-methoxyphenyl)-6-methyl-2-oxo-1,2,3,4-tetrahydropyrimidine-5-carboxamide421576-74-1C21H23N3O5
- (4aR,6S,7R,8R,8aS)-7-Azido-8-(benzyloxy)-6-methoxy-2-phenylhexahydropyrano[3,2-d][1,3]dioxine162678-87-7C21H23N3O5
- 4-(Furan-2-carbonyl)-3-hydroxy-1-(3-morpholinopropyl)-5-(pyridin-2-yl)-1H-pyrrol-2(5H)-one618878-19-6C21H23N3O5
- 4-(Furan-2-carbonyl)-3-hydroxy-1-[3-(morpholin-4-yl)propyl]-5-(pyridin-4-yl)-2,5-dihydro-1H-pyrrol-2-one378208-55-0C21H23N3O5
- 2-((((9H-Fluoren-9-yl)methoxy)carbonyl)amino)-5-ureidopentanoic acid161125-34-4C21H23N3O5
- 2-Methyl-3-(morpholine-4-carbonyl)-4-(4-nitrophenyl)-4,6,7,8-tetrahydro-1H-quinolin-5-one423137-16-0C21H23N3O5
- Prop-2-enyl 5-(4-methoxyphenyl)-1,3,7-trimethyl-2,4-dioxo-5,8-dihydropyrido[2,3-d]pyrimidine-6-carboxylate622360-78-5C21H23N3O5
- Prop-2-enyl 5-(3-methoxyphenyl)-1,3,7-trimethyl-2,4-dioxo-5,8-dihydropyrido[2,3-d]pyrimidine-6-carboxylate622360-96-7C21H23N3O5
- 2-Amino-4-(3,4-dimethoxyphenyl)-6-(2-methoxyethyl)-7-methyl-5-oxo-5,6-dihydro-4H-pyrano[3,2-c]pyridine-3-carbonitrile880794-96-7C21H23N3O5
- (4-Methoxyphenyl)[8-(4-nitrophenyl)-1-oxa-4,8-diazaspiro[4.5]dec-4-yl]methanone339011-69-7C21H23N3O5
- N-(2,5-Dimethoxyphenyl)-4-(2-methoxyphenyl)-6-methyl-2-oxo-1,2,3,4-tetrahydropyrimidine-5-carboxamide421576-85-4C21H23N3O5
- N-[(E)-(3,4-Dimethoxyphenyl)methylideneamino]-1-(4-methoxyphenyl)-5-oxopyrrolidine-3-carboxamide351188-73-3C21H23N3O5
- 5-(Furan-2-yl)-3-hydroxy-4-isonicotinoyl-1-(3-morpholinopropyl)-1H-pyrrol-2(5H)-one844463-88-3C21H23N3O5
- 4-{[1-(3-Methoxy-2-methyl-2H-indazole-6-carbonyl)piperidin-4-yl]oxy}-6-methyl-2H-pyran-2-one1788680-68-1C21H23N3O5
- N-Propan-2-yl-2-[3-(3,4,5-trimethoxyphenyl)-1,2,4-oxadiazol-5-yl]benzamide876713-11-0C21H23N3O5
- 2-(2,4-Dimethylphenyl)-N-[5-(3,4,5-trimethoxyphenyl)-1,3,4-oxadiazol-2-yl]acetamide941896-02-2C21H23N3O5
- N-[3-(Acetylamino)phenyl]-1-(2,4-dimethoxyphenyl)-5-oxopyrrolidine-3-carboxamide924964-85-2C21H23N3O5
- 2-(6,7-Dimethoxy-4-oxoquinazolin-3(4H)-yl)-N-[2-(4-methoxyphenyl)ethyl]acetamide930858-82-5C21H23N3O5
- 4-((2-Cyanophenyl)amino)-2-((3,4-dimethoxyphenethyl)amino)-4-oxobutanoic acid1047678-66-9C21H23N3O5
- 2-(3-(Benzo[d][1,3]dioxol-5-yl)-2-oxoimidazolidin-1-yl)-N-benzyl-N-(2-hydroxyethyl)acetamide1323298-61-8C21H23N3O5
- 2-[7,8-Dimethoxy-1-oxo-2(1H)-phthalazinyl]-N~1~-(2-methoxyphenethyl)acetamide1282128-83-9C21H23N3O5
- 2-[7,8-Dimethoxy-1-oxo-2(1H)-phthalazinyl]-N~1~-(4-methoxyphenethyl)acetamide1282107-63-4C21H23N3O5
- 4-Benzyl-5-[4-(furan-2-carbonyl)piperazine-1-carbonyl]morpholin-3-one1351581-26-4C21H23N3O5
- 2-Oxo-6-(3-(2,3,4-trimethoxyphenyl)propanoyl)-1,2,5,6,7,8-hexahydro-1,6-naphthyridine-3-carbonitrile2034485-73-7C21H23N3O5
- 4-[3-(3,4-Dimethoxyphenyl)-1,2,4-oxadiazol-5-yl]-N-(4-methoxyphenyl)butanamide878981-18-1C21H23N3O5
- N-Cyclohexyl-2-{[(4-nitrophenoxy)acetyl]amino}benzamide714278-56-5C21H23N3O5
- N-[(E)-(2,5-Dimethoxyphenyl)methylideneamino]-1-(4-methoxyphenyl)-5-oxopyrrolidine-3-carboxamide352454-10-5C21H23N3O5
- 3-Butoxy-N-[5-(3,4-dimethoxyphenyl)-1,3,4-oxadiazol-2-yl]benzamide899734-66-8C21H23N3O5
- N-[4-(3,4-Dimethoxyphenyl)-1,2,5-oxadiazol-3-yl]-2-(2,3-dimethylphenoxy)propanamide874145-28-5C21H23N3O5
- N-[4-(3,4-Dimethoxyphenyl)-1,2,5-oxadiazol-3-yl]-4-(2-methylpropoxy)benzamide898616-62-1C21H23N3O5
- 2-Amino-4-(4-ethoxy-3-methoxyphenyl)-6-(2-hydroxyethyl)-7-methyl-5-oxo-4H,5H,6H-pyrano[3,2-c]pyridine-3-carbonitrile884217-32-7C21H23N3O5
- 3-[1-(2,3-Dihydro-1,4-benzodioxin-6-yl)-5-oxopyrrolidin-3-yl]-1-[(4-methoxyphenyl)methyl]urea891112-34-8C21H23N3O5
- 1-(1-(2,3-Dihydrobenzo[b][1,4]dioxin-6-yl)-5-oxopyrrolidin-3-yl)-3-(4-ethoxyphenyl)urea891113-38-5C21H23N3O5
- 2-(6,7-Dimethoxy-4-oxoquinazolin-3(4H)-yl)-N-[2-(2-methoxyphenyl)ethyl]acetamide1081140-32-0C21H23N3O5
- 3-(4-(5-Isopropyl-1,3,4-oxadiazol-2-yl)piperidine-1-carbonyl)-8-methoxy-2H-chromen-2-one1208947-00-5C21H23N3O5
- Phenyl 4-({[(2H-1,3-benzodioxol-5-yl)carbamoyl]amino}methyl)piperidine-1-carboxylate1235029-03-4C21H23N3O5
- N-[2-Hydroxy-2-(5-methylfuran-2-yl)ethyl]-N'-{2-oxo-1-azatricyclo[7.3.1.0^{5,13}]trideca-5,7,9(13)-trien-7-yl}ethanediamide1251579-37-9C21H23N3O5
- 3-(Benzo[d][1,3]dioxol-5-ylmethyl)-N-(2-(cyclohex-1-en-1-yl)ethyl)-2,4-dioxo-1,2,3,4-tetrahydropyrimidine-5-carboxamide1421585-53-6C21H23N3O5
- (E)-N-((5-(Furan-2-yl)-1-methyl-1H-pyrazol-3-yl)methyl)-3-(3,4,5-trimethoxyphenyl)acrylamide1421588-02-4C21H23N3O5
- N1-(benzo[d][1,3]dioxol-5-yl)-N2-(2-(2,3-dihydrobenzofuran-5-yl)-2-(dimethylamino)ethyl)oxalamide1428380-19-1C21H23N3O5
- N-[3-(Furan-3-yl)-3-hydroxypropyl]-N'-{2-oxo-1-azatricyclo[7.3.1.0^{5,13}]trideca-5,7,9(13)-trien-7-yl}ethanediamide1428349-32-9C21H23N3O5
- (5Z)-5-[4-(Diethylamino)-2-methoxybenzylidene]-1-(furan-2-ylmethyl)pyrimidine-2,4,6(1H,3H,5H)-trione1049976-49-9C21H23N3O5
- N-(1-Acetyl-3,4-dihydro-2H-quinolin-7-yl)-N'-(3,4-dimethoxyphenyl)oxamide898413-34-8C21H23N3O5
- 4-Butoxy-N-[5-(3,4-dimethoxyphenyl)-1,3,4-oxadiazol-2-yl]benzamide899963-40-7C21H23N3O5
- 2-Butoxy-N-[4-(3,4-dimethoxyphenyl)-1,2,5-oxadiazol-3-yl]benzamide874207-38-2C21H23N3O5
- N-(Benzoyloxy)-2-[N-(benzoyloxy)carbamimidoyl]-3-methylpentanimidic acid93974-11-9C21H23N3O5
- N-[4-(3,4-Dimethoxyphenyl)-1,2,5-oxadiazol-3-yl]-2-(3,4-dimethylphenoxy)propanamide874145-25-2C21H23N3O5
- N-[4-(3,4-Dimethoxyphenyl)-1,2,5-oxadiazol-3-yl]-2-(4-ethylphenoxy)propanamide874146-61-9C21H23N3O5
- N-[4-(3,4-Dimethoxyphenyl)-1,2,5-oxadiazol-3-yl]-2-(3,5-dimethylphenoxy)propanamide874398-90-0C21H23N3O5
- 2-(2-Methoxyphenoxy)-N-{4-[4-(propan-2-yloxy)phenyl]-1,2,5-oxadiazol-3-yl}propanamide898616-56-3C21H23N3O5
- 1-(Benzo[d][1,3]dioxol-5-yl)-3-((1-(4-ethoxyphenyl)-5-oxopyrrolidin-3-yl)methyl)urea954636-31-8C21H23N3O5
- 1-((1-(Benzo[d][1,3]dioxol-5-yl)-5-oxopyrrolidin-3-yl)methyl)-3-(4-ethoxyphenyl)urea954660-79-8C21H23N3O5
- 1-((1-(Benzo[d][1,3]dioxol-5-yl)-5-oxopyrrolidin-3-yl)methyl)-3-(2-ethoxyphenyl)urea954589-29-8C21H23N3O5
- 1-((1-(Benzo[d][1,3]dioxol-5-yl)-5-oxopyrrolidin-3-yl)methyl)-3-(4-methoxybenzyl)urea954589-35-6C21H23N3O5
- N-{2-[(2,5-Dimethoxyphenyl)amino]-2-oxoethyl}-5-methoxy-1-methyl-1H-indole-2-carboxamide951974-23-5C21H23N3O5
- 4,5-Dimethoxy-N-{3-[(3-methoxyphenyl)amino]-3-oxopropyl}-1H-indole-2-carboxamide951975-01-2C21H23N3O5
- 4,7-Dimethoxy-N-{2-[(3-methoxyphenyl)amino]-2-oxoethyl}-1-methyl-1H-indole-2-carboxamide951975-96-5C21H23N3O5
- N-(2-{[(3,4,5-Trimethoxyphenyl)carbonyl]amino}ethyl)-1H-indole-2-carboxamide951965-05-2C21H23N3O5
- 4,6-Dimethoxy-N-{2-[(3-methoxyphenyl)amino]-2-oxoethyl}-1-methyl-1H-indole-2-carboxamide951996-53-5C21H23N3O5
Frequently asked questions
What is the molar mass of C21H23N3O5?
The molar mass of C21H23N3O5 is 397.43 g/mol, calculated from standard atomic weights for 21 carbon atoms, 23 hydrogen atoms, 3 nitrogen atoms and 5 oxygen atoms. The monoisotopic mass is 397.1638 Da.
How many compounds have the formula C21H23N3O5?
CompoundList lists 165 compounds with the molecular formula C21H23N3O5, including Strychnidin-10-one, nitrate (1:1), Abexinostat, Navarixin anhydrous. 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 C21H23N3O5?
C21H23N3O5 has a degree of unsaturation of 12. 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.