1. A method of treating ADHD, comprising administering a therapeutically effective amount of a compound of formula (I) or a pharmaceutically acceptable salt thereof to a mammal in need thereof: where: R is selected from the group consisting of hydrogen, lower alkyl containing from 1 to 8 atoms carbon, a halogen selected from F, Cl, Br and I, an alkoxy group containing from 1 to 3 carbon atoms, a nitro group, a hydroxyl group, a trifluoromethyl group and a thioalkoxy group containing from 1 to 3 carbon atoms； x is an integer from 1 up to 3, under the condition that R may be the same or different when x is 2 or 3； R and R may be the same or different from each other and independently selected from the group consisting of hydrogen, lower alkyl containing from 1 to 8 carbon atoms, aryl, arylalkyl cycloalkyl containing from 3 to 7 carbon atoms； R and R can be combined to form a 5-7 membered heterocyclic ring substituted by a radical selected from the group consisting of hydrogen, alkyl and aryl, wherein said heterocycle contains from 1 to 2 atoms nitrogen and 0-1 oxygen atom and atom Nitrogen is not directly bonded to each other or to the oxygen atom. 2. The method according to claim 1, characterized in that R is hydrogen and x = 1.3. The method according to claim 1, characterized in that R, R and R are hydrogen and x = 1.4. A method according to claim 1, characterized in that the compound having structural formula (I) is an enantiomer substantially free of other enantiomers, or a mixture of enantiomers in which one enantiomer of a compound having structural formula (I) predominates. The method according to claim 4, characterized in that one enantiomer predominates in quantity at1. Способ лечения ADHD, включающий введение терапевтически эффективного количества соединения, имеющего формулу (I), или его фармацевтически приемлемой соли млекопитающему, нуждающемуся в этом:где:R выбран из группы, состоящей из водорода, низшего алкила, содержащего от 1 до 8 атомов углерода, га
