A series of 2-(substituted phenoxyacetoxy)alkyl-5,5-dimethyl-1,3,2- dioxaphosphinan-2-ones IIa-s were designed and synthesized on the basis of the previous work for the modification of alkylphosphonates I, and their structures were confirmed by 1H NMR, 31P NMR, 13C NMR, IR, MS, and elemental analysis. Their herbicidal activities against seven species of weeds were evaluated in a greenhouse. A part of the title compounds such as IIa-g, IIk, IIo, and IIr exhibited significant postemergence herbicidal activity against Abutilon theophrasti, Brassica juncea, Amaranthus retroflexus, and Eclipta pros...