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Oxacillin

Athanor · official

C19H19N3O5S · 401.4 g/mol

IUPAC name: 3,3-dimethyl-6-[(5-methyl-3-phenyl-1,2-oxazole-4-carbonyl)amino]-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylic acid

Also called Bactocill, penicillinase-resistant

Drugs
Open in Athanor
The structure of Oxacillin
Drawn from its SMILES with RDKit

Names and identifiers

IUPAC name
3,3-dimethyl-6-[(5-methyl-3-phenyl-1,2-oxazole-4-carbonyl)amino]-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylic acid
Synonyms
Bactocill, penicillinase-resistant, 3,3-dimethyl-6-[(5-methyl-3-phenyl-1,2-oxazole-4-carbonyl)amino]-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylic acid
+ 17 more

3,3-dimethyl-6-[[(5-methyl-3-phenyl-4-isoxazolyl)-oxomethyl]amino]-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylic acid, MPI-penicillin; MPi-PC, Oprea1_168564, Oprea1_662776, CHEMBL3305959, SCHEMBL14126543, CHEBI:94315, DTXSID70859062, EBC-97021, STA013953, AKOS000641644, SR-01000316163, SR-01000316163-1, BRD-A03044413-236-01-3, Q27166135, 3,3-dimethyl-6-(5-methyl-3-phenyl-1,2-oxazole-4-amido)-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylic acid, 3,3-Dimethyl-6-(5-methyl-3-phenyl-1,2-oxazole-4-carboxamido)-7-oxo-4-thia-1-azabicyclo[3.2.0]heptane-2-carboxylic acid

Molecular formula
C19H19N3O5S
Empirical formula
C19H19N3O5S
Molecular weight
401.4 g/mol
Exact mass
401.10454
CAS number
66-79-5
PubChem CID
4608
Canonical SMILES
CC1=C(C(=NO1)C2=CC=CC=C2)C(=O)NC3C4N(C3=O)C(C(S4)(C)C)C(=O)O
Isomeric SMILES
CC1=C(C(=NO1)C2=CC=CC=C2)C(=O)NC3C4N(C3=O)C(C(S4)(C)C)C(=O)O
InChI
InChI=1S/C19H19N3O5S/c1-9-11(12(21-27-9)10-7-5-4-6-8-10)15(23)20-13-16(24)22-14(18(25)26)19(2,3)28-17(13)22/h4-8,13-14,17H,1-3H3,(H,20,23)(H,25,26)
InChIKey
UWYHMGVUTGAWSP-UHFFFAOYSA-N
Molfile

Names, InChI and the identifiers from PubChem, retrieved 2026-10-14.

Calculated

Heavy atoms
28
Rings
4
Aromatic rings
2
Fraction sp³ carbons (Fsp3)
0.37
H-bond donors
2
H-bond acceptors
6 computed here · PubChem 7
Rotatable bonds
4
TPSA (Ų)
112.7 computed here · PubChem 138
Formal charge
0
XLogP3
2.4 PubChem
Complexity
680 PubChem
Stereocenters
0 defined, 3 undefinedCIP: C16: undefined · C20: undefined · C28: undefined
Double-bond geometry
None specified
Point group
C1 of one 3D conformer with its hydrogens, by Athanor’s engine (as in the app)

Elemental analysis

  • C56.85%
  • H4.77%
  • N10.47%
  • O19.93%
  • S7.99%

Isotope pattern

100%401.10423%402.1088.0%403.1041.4%404.106405.107

Each peak is a nominal mass with its abundance-weighted exact mass, as a percentage of the tallest, from IUPAC natural isotope abundances.

Computed from the structure with RDKit 2026.09 when this page was built, beside PubChem's own computed values from its record; where the two differ, both are shown.

Predicted

log P
1.9 Crippen (Wildman and Crippen 1999)
log S (water solubility)
-3.55 ESOL (Delaney 2004), log mol/L
Synthetic accessibility
3.47 SA score, 1 easy to 10 hard (Ertl and Schuffenhauer 2009)

Drug-likeness: Lipinski’s rule of five

  • Molecular weight ≤ 500: 401.44
  • log P ≤ 5 (Crippen): 1.9
  • H-bond donors ≤ 5: 2
  • H-bond acceptors ≤ 10: 6

Passes all four rules.

¹³C NMR shifts, predicted

Predictions, not measurements; each names its method. A measured log P, where a source reports one, is under Physical properties.

Safety

No GHS hazard classification was found in the sources.

Safety data sheets on the supplier’s page: Mcule, BenchChem, Glentham Life Sciences Ltd..

Always read the supplier’s safety data sheet before working with it.

Literature

Reading PubChem, OpenAlex and GSRS…

Bioactivity

Reading ChEMBL…

References

  1. ·Calculated values: computed by Athanor with RDKit 2026.09 from the structure.
  2. ·Literature on PubChem

Data last updated 2026-10-14.