Design of pyrazole benzophenones as potent HPPD inhibitors with excellent herbicidal activities.

N‐phenoxyacetyl‐1,3‐oxazolidine derivatives were synthesized by the cyclization and acylation with β‐amino alcohol, ketone, and phenoxyacetyl chloride as the starting materials. All compounds were characterized by IR, 1H NMR, 13C NMR, ESI‐MS, and elemental analysis. The configuration of 4a was determined by X‐ray crystallography. The preliminary biological tests showed that all products could protect soybean against injury caused by 2,4‐D butylate to some extent.

A two-step sequence was developed for synthesising different disubstituted 6,7-dichloro-1,2,3,4-tetrahydroquinoxalines without blocking the reactive centres. N-dichloroacetyl-6,7-dichloro-1,2,3,4-tetrahydroquinoxaline was prepared from 6,7-dichloro-1,2,3,4-tetrahydroquinoxaline and dichloroacetyl chloride giving N-acyl-N ʹ-dichloroacetyl-6,7-dichloro-1,2,3,4tetrahydroquinoxalines. The structures of all the compounds were characterised by IR, 1 H NMR, 13 C NMR, and elemental analysis. The structure was determined by X-ray crystallography.