Synthesis and herbicidal activity of 2-(substituted phenoxyacetoxy)alkyl-5,5-dimethyl-1,3,2-dioxaphosphinan-2-one containing fluorine

A series of novel 2-(substituted phenoxyacetoxy)alkyl-5,5-dimethyl-1,3,2-dioxaphosphinan-2-one bearing fluorine 5a-n and fluorine free 5o-q were designed and synthesized. The results of bioassay showed that some of the target compounds exhibited excellent herbicidal activities to Abutilon theophrasti, Brassica juncea, Amaranthus retroflexus and Eclipta prostrata in post-emergence treatment at a dosage of 150 g ai/ha. It could be found that the type and position of fluorine-containing group as X or Y on benzene ring had a very important effect on herbicidal activity. Compound 5l 2-[(2-chloro-4-fluorophenoxy)acetoxy](methyl)methyl-5,5-dimethyl-1,3,2-dioxaphosphinan-2-one showed notable herbicidal activity, with 100% inhibition against A. theophrasti and A. retroflexus; and compound 5m 2-(3-trifluoromethylphenoxyacetoxy)(methyl)methyl-5,5-dimethyl-1,3,2-dioxaphosphinan-2-one with 100% inhibition against A. theophrasti even at a dosage of 75 g ai/ha. Additional crop selectivity testing showed that compounds 5g 2-(3-trifluoromethylphenoxyacetoxy)(phenyl)methyl-5,5-dimethyl-1,3,2-dioxaphosphinan-2-one and 5l are safe to rice, corn, cotton, rape and wheat.