We have investigated the biologically active conformation of the non-steroidal ecdysone agonist, 1-tert-butyl-1, 2-dibenzoylhydrazine (RH-5849) by means of design, synthesis and conformational analysis of cyclic derivatives of RH-5849. Among the synthesized compounds, a 6-membered cyclic hydrazine bearing two benzoyl groups (5) exists in three conformational states in solution, and the major unsymmetrical conformer of 5 is similar to ...