The (6a,11b,16a,17a)-6,9-Difluoro-11,17-dihydroxy-16-methyl-3-oxoandrosta-1,4-diene-17-carboxylic acid methyl ester ,its cas register number is 28416-84-4. It also can be called as Androsta-1,4-diene-17b-carboxylic acid, 6a,9-difluoro-11b,17-dihydroxy-16a-methyl-3-oxo-, methyl ester(8CI) . Its systematic name is methyl (6alpha,11beta,16alpha,17alpha)-6,9-difluoro-11,17-dihydroxy-16-methyl-3-oxoandrosta-1,4-diene-17-carboxylate . The index of refraction about it is 1.561, molar refractivity is 100.539 cm³ , molar volume is 310.479 cm³ and surface tension is 49.319 dyne/cm, also, it have other chemical properties, for example, the enthalpy of vaporization about this chemicals is 89.719 kJ/mol, vapour pressure is 0 mmHg at 25 °C and so on.

The (6a,11b,16a,17a)-6,9-Difluoro-11,17-dihydroxy-16-methyl-3-oxoandrosta-1,4-diene-17-carboxylic acid methyl ester  is a Fluticasone intermediate.

This chemicals can be described computed from structure:
1) SMILES: COC(=O)[C@]2(O)[C@@]3(C)C[C@H](O)[C@]4(F)[C@@]\1(C)/C=C\C(=O)/C=C/1[C@@H](F)C[C@H]4[C@@H]3C[C@H]2C
2) InChI: InChI=1/C22H28F2O5/c1-11-7-13-14-9-16(23)15-8-12(25)5-6-19(15,2)21(14,24)17(26)10-20(13,3)22(11,28)18(27)29-4/h5-6,8,11,13-14,16-17,26,28H,7,9-10H2,1-4H3/t11-,13+,14+,16+,17+,19+,20+,21+,22+/m1/s1
3) InChIKey: HTJSTTZFHWMHDB-GQKYHHCABJ