Preparation and Root Growth-Inhibitory Activity of N-Substituted 2-(2-Chloroacetamido)-3-(furan-2-yl)propanamides

A series of N-substituted 2-(2-chloroacetamido)-3-(furan-2-yl)propanamides (16—18) was prepared through the reaction of chloroacetyl chloride with N-substituted 2-amino-3-(furan-2-yl)propanamides (15), which were obtained via condensation of 2-(tert-butoxycarbonylamido)-3-(furan-2-yl)propanoic acid (Boc-furylalanine) (8) with amines (9, 11, 13), followed by hydrolysis of the resultant N-substituted Boc-furylalanine acid amides (10, 12, 14) in the presence of HCl/dioxane. The biological activity of the prepared 16, 17 and 18 as root growth inhibitors was examined by germination assay using rape seed. At the concentration of 5.0×10−5 M, the most active compound, 2-(2-chloroacetamido)-N-(2,6-diethylphenyl)-3-(furan-2-yl)propanamide (16n), showed potent root growth-inhibitory activity of 76% towards rape seedlings.