A four-step synthesis of 1-substituted 5-(2-aminophenyl)-1H-pyrazoles 5 as a novel type of histamine analogs and versatile building blocks for further transformations was developed. The synthesis starts from commercially available 2-nitroacetophenone (12), which is converted into the enamino ketone 13 as the key intermediate. Cyclization of the key intermediate 13 with monosubstituted hydrazines 14a -14l afforded the 5-(2-nitrophenyl)-1H-pyrazoles 17a -17l. Finally, catalytic hydrogenation of the nitro compounds 17a, 17c -17e, and 17g -17j furnished the title compounds 5a, 5c -5e, and 5g -5j, respectively, in good yields. As demonstrated by some further transformations, additional functionalization of compounds 17 and 5 is feasible, either by electrophilic substitution at C(4) of the pyrazole ring, or at the NH 2 group.Introduction. -In biological processes, histamine, tyramine, dopamine, tryptamine, serotonin, and melatonin play a crucial role as chemical messengers. Therefore, preparation of their novel synthetic analogs based on the 2-(heteroaryl)ethylamine scaffold is an important target in medicinal and synthetic organic chemistry [1].Pyrazoles are an important class of heterocyclic compounds. Despite their rare occurrence in nature, numerous pyrazole derivatives have found use in various applications, and a general interest in their chemistry is still continuing (for a review, see [2]). Among numerous synthetic options for the construction of the pyrazole ring, two classical approaches are most frequently employed: a) cyclocondensation of a 1,3-dicarbonyl compound with a hydrazine derivative and b) 1,3-dipolar cycloaddition of a CÀNÀN type 1,3-dipole (diazoalkane, nitrile imine, or azomethine imine) to a C,C multiple bond [2].Recently, a part of our research has been focused on the synthesis of functionalized pyrazoles utilizing the