Bolasterone (, ) (brand names Myagen, Methosarb; former developmental code name U-19763), also known as 7ñ,17ñ-dimethyltestosterone, is a 17ñ-alkylated androgen/anabolic steroid (AAS) which is used in veterinary medicine. It has close structural similarity to testosterone, and like methyltestosterone has a methyl group at C17ñ in order to increase oral bioavailability. In addition, it is also 7ñ-methylated, similar to its 7ò-methylated isomer calusterone. The medication has a low to moderate ratio of anabolic to androgenic activity, similar to that of fluoxymesterone.
Bolasterone is on the World Anti-Doping Agency's list of prohibited substances, and is therefore banned from use in most major sports.
The chemical synthesis was reported: Patent:
The oxidation of methyltestosterone [58-18-4] (1) with chloranil gives 17alpha-methyl-6,7-dehydrotestosterone [5585-85-3] (2). The conjugate addition of methylmagnesium bromide in the presence of a catalytic amount of cuprous iodide (c.f. Gilman reagent) gives a mixture of bolasterone and calusterone, with the former predominating.