According to the data of theorstical conformational analysis, in the amide Ilb a trans- conformation of the fragment N--C--C--N predominates, while in the amide IIIb this fragment is practically fixed in a gauche conformation. On the basis of the results obtained we hypothesized that in the interaction of I and its amide analogs II~ and IIIb with nicstine cholinoreceptors, the gauche-conformation of the fragments OC--C--N (in I) and N--C--C--N (in IIb and IIIb) is active. Continuing ...