Synthesis, Crystal Structure, Herbicidal Activity, and SAR Study of Novel -(Arylmethoxy)-2-chloronicotinamides Derived from Nicotinic Acid.

Nicotinic acid, also known as niacin, is a natural product, which is widely found in plants and animals. To discover novel natural-product-based herbicides, a series of -(arylmethoxy)-2-chloronicotinamides were designed and synthesized. Some of the new -(arylmethoxy)-2-chloronicotinamides exhibited excellent herbicidal activity against (bentgrass) at 100 μM. Compound (2-chloro--((3,4-dichlorobenzyl)oxy)nicotinamide) possessed excellent herbicidal activity against (duckweed), with an IC value of 7.8 μM, whereas the commercial herbicides clomazone and propanil had values of 125 and 2 μM, respectively. The structure-activity relationships reported in this paper could be used for the development of new herbicides against monocotyledonous weeds.