Preparation and Root Growth-Modulatory Activity of N-Substituted 2-Acetylamino-2-ethoxycarbonyl-3-(2-furyl)propanamides

N-Substituted 2-acetylamino-2-ethoxycarbonyl-3-(2-furyl)propanamides(8)were synthesized through the reaction of amines(13)with 2-acetylamino-2-ethoxycarbonyl-3-(2-furyl)propanoic acid(3b), which was prepared via condensation of 2-(bromomethyl)furan(10b)with diethyl acetamidomalonate, followed by partial hydrolysis of the resultant diethyl ester(3a)in the presence of barium hydroxide. However, bulky amines such as tert-butylamine or 2-trifluoromethylaniline did not afford the corresponding diamides(8). The biological activity of the prepared diamides(8)as root growth modulators was examined by germination assay using rape and leek seeds. N-(5-Bromo-2-thiazolyl)-and N-(4-chloro-2-benzothiazolyl)-2-acetylamino-2-ethoxycarbonyl-3-(2-furyl)propanamides(8h, i)both potently inhibited the root growth of rape seedlings, but were less effective in the case of leek seeds. The herbicide 2, 4-dichlorophenoxyacetic acid completely inhibited root growth in both cases.