Mibolerone, also known as dimethylnortestosterone (DMNT) and sold under the brand names Cheque Drops and Matenon, is a synthetic, orally active, and extremely potent anabolic–androgenic steroid (AAS) and a 17α-alkylated nandrolone (19-nortestosterone) derivative which was marketed by Upjohn for use as a veterinary drug.

[3][4][5] It was indicated specifically as an oral treatment for prevention of estrus (heat) in adult female dogs.

The first step involves extending the conjugation of the enone function by an additional double bond.

Chloranil (tetrachloroquinone) is the forerunner of dichlorodicyanoquinone (DDQ), a reagent used extensively for introducing additional unsaturation in the progestin and corticoid series.

Enamines are commonly used to activate adjacent functions; they are also not infrequently used, as in this case, as protecting groups.