Title: Clostebol
CAS Registry Number: 1093-58-9
CAS Name: (17b)-4-Chloro-17-hydroxyandrost-4-en-3-one
Additional Names: 4-chlorotestosterone
Molecular Formula: C19H27ClO2
Molecular Weight: 322.87
Percent Composition: C 70.68%, H 8.43%, Cl 10.98%, O 9.91%
Literature References: Prepn: Camerino et al., Farmaco Ed. Sci. 11, 586 (1956); eidem, J. Am. Chem. Soc. 78, 3540 (1956); Ringold et al., J. Org. Chem. 21, 1432 (1956); Camerino, US 2953582 (1960 to Farmitalia); Julian, Printy, US 2933510 (1960 to Julian Labs.). Clinical pharmacology of the acetate: Molinatti et al., Folia Endocrinol. 14, 528 (1961); Krueskemper, Morgner, Int. Z. Klin. Pharmakol. Ther. Toxikol. 1, 455 (1968).
Properties: Crystals from acetone + hexane, mp 188-190°. [a]D20 +148° (CHCl3). uv max (95% ethanol): 256 nm (log e 4.13).
Melting point: mp 188-190°
Optical Rotation: [a]D20 +148° (CHCl3)
Absorption maximum: uv max (95% ethanol): 256 nm (log e 4.13)
Derivative Type: Acetate
CAS Registry Number: 855-19-6
Trademarks: Macrobin; Steranabol (Farmitalia)
Molecular Formula: C21H29ClO3
Molecular Weight: 364.91
Percent Composition: C 69.12%, H 8.01%, Cl 9.72%, O 13.15%
Properties: Crystals from methanol, mp 228-230°. [a]D +118 ±4° (CHCl3). uv max: 255 nm (e 13,300). Sol in ethanol.
Melting point: mp 228-230°
Optical Rotation: [a]D +118 ±4° (CHCl3)
Absorption maximum: uv max: 255 nm (e 13,300)
NOTE: This is a controlled substance (anabolic steroid): 21 CFR, 1308.13, as defined in 1300.01.
Therap-Cat: Anabolic.
Keywords: Anabolic.
Clothiapine Clotiazepam Clove Cloxacillin Cloxazolam

Systematic (IUPAC) name
(8S,9S,10R,13S,14S,17S)-4-chloro-17-hydroxy-10,13-dimethyl- 1,2,6,7,8,9,11,12,14,15,16,17-dodecahydrocyclopenta[a]phenanthren-3-one
Clinical data
Legal status  ?
CAS number 1093-58-9
ATC code None
PubChem CID 68947
DrugBank DB01521
ChemSpider 62171 YesY
KEGG D07731 YesY
Chemical data
Formula C19H27ClO2 
Mol. mass 322.869 g/mol
 YesY (what is this?)  (verify)

Clostebol (INN), usually as the ester clostebol acetate or clostebol enanthate, is a synthetic anabolic androgenic steroid. Clostebol is the 4-chloro derivative of the natural hormone testosterone.

It is a weak anabolic steroid which was used by athletes from the German Democratic Republic (East Germany).[citation needed] It is a version of testosterone that is chlorinated so as to prevent conversion to dihydrotestosterone (DHT) while also rendering the chemical incapable of conversion to estrogen.