Process for preparing a compound of formula wherein R 1 and R 2 represent, independently of one another, a hydrogen atom, an alkyl radical comprising from 1 to 3 carbon atoms, or a halogen atom, or else R 1 and R 2 together form a carbon-based ring comprising from 4 to 6 carbon atoms, ortho-fused to the B ring of the compound, said ring optionally comprising one or more double bonds and being optionally substituted with one or more alkyl groups comprising 1 to 3 carbon atoms, or else R 1 and R 2 together form the C and D rings of a steroidal carbon-based backbone, said C and D rings optionally comprising one or more double bonds and being optionally substituted with one or more groups chosen from linear or branched alkyl groups comprising from 1 to 12 carbon atoms, acyl groups comprising from 1 to 12 carbon atoms and optionally substituted with one or more hydroxyl groups, carboxyl, hydroxyl or oxo groups, in free or protected form, or halogen atoms, preferentially fluorine, it being possible for each position of said C and D rings to bear one or, when this is possible, two substituents, R' 1 represents a hydrogen or halogen atom, preferentially fluorine, and R 1 and R' 1 are located on either side of the plane of the A and B rings, R 3 represents an alkyl group comprising from 1 to 4 carbon atoms, preferentially a methyl group, preferentially a methyl group positioned in the α position, represents a single bond or a double bond, and represents either a single bond in the α or β position of the A and B rings, or a double bond in the plane of the A and B rings, comprising a step of alkylation of a compound of formula wherein R 1, R' 1 and R 2, and are as defined in the compound, wherein X is a halogen atom, preferentially bromine or iodine, preferentially bromine, with an organometallic alkylating agent which makes it possible to introduce an alkyl group R 3 as a replacement for the halogen atom X of the compound, optionally in the presence of a metal catalyst, preferentially a palladium or copper catalyst, so as to result in the compound of formula. wherein R 1 and R 2 represent, independently of one another, a hydrogen atom, an alkyl radical comprising from 1 to 3 carbon atoms, or a halogen atom, or else R 1 and R 2 together form a carbon-based ring comprising from 4 to 6 carbon atoms, ortho-fused to the B ring of the compound, said ring optionally comprising one or more double bonds and being optionally substituted with one or more alkyl groups comprising 1 to 3 carbon atoms, or else R 1 and R 2 together form the C and D rings of a steroidal carbon-based backbone, said C and D rings optionally comprising one or more double bonds and being optionally substituted with one or more groups chosen from linear or branched alkyl groups comprising from 1 to 12 carbon atoms, acyl groups comprising from 1 to 12 carbon atoms and optionally substituted with one or more hydroxyl groups, carboxyl, hydroxyl or oxo groups, in free or protected form, or halogen atoms, preferentially fluorine, it being possible for each position of said C and D rings to bear one or, when this is possible, two substituents, R' 1 represents a hydrogen or halogen atom, preferentially fluorine, and R 1 and R' 1 are located on either side of the plane of the A and B rings, R 3 represents an alkyl group comprising from 1 to 4 carbon atoms, preferentially a methyl group, preferentially a methyl group positioned in the α position, represents a single bond or a double bond, and represents either a single bond in the α or β position of the A and B rings, or a double bond in the plane of the A and B rings, comprising a step of alkylation of a compound of formula wherein R 1, R' 1 and R 2, and are as defined in the compound, wherein X is a halogen atom, preferentially bromine or iodine, preferentially bromine, with an organometallic alkylating agent which makes it possible to introduce an alkyl group R 3 as a replacement for the halogen atom X of the compound, optionally in the presence of a metal catalyst, preferentially a palladium or copper catalyst, so as to result in the compound of formula.