Synthesis and Octopaminergic-Agonist Activity of 2-(Arylimino)oxazolidines and 2-(Substituted Benzylamino)-2-oxazolines

2-(Arylimino)oxazolidines (AIOs) and 2-(substituted benzylamino)-2-oxazolines (SBOs) were obtained by cyclodesulfurizing the corresponding thiourea with yellow mercuric oxide. The activity for stimulating adenylate cyclase prepared from thoracic nerve cords of the American cockroach Periplaneta americana L. was examined by these compounds. Greater enzyme activation appeared to result from alkyl substitution at the 2, 6-positions or 2-alkyl 4-halogen at the phenyl ring of AIOs. A halogen in the m- and/or p-position, or methyl group at p-position seems to be a favorable substituent on the phenyl ring of SBO compounds for octopaminergic-agonist activity. SBO with a 3, 4-dichlorophenyl group (36) was less active than its thiazoline derivative, 2-(3, 4-dichlorophenylamino)-2-thiazoline (CBT) in terms of K_a and V_max: K_a and V_max of 36 were 2.3 µm and 29% relative to OA, whereas those of CBT have been 0.40 µm and 53% relative to OA, respectively. Superimposition of energy-minimized OA and CBT revealed structural and conformational similarities that might account for the high activity of CBT.