Caged bicyclic phosphate

The l,2-diacyl-l-/-butylhydrazines have been found to be effective as insect-growth regulators. Caged bicyclic phosphates have also shown promise as insecticides. Wang and Huang have combined these effects in the synthesis of compounds 266 and 267 <2000PS(161)173>. Compounds 268 and 269 have been synthesized for their potential... 

In order to obtain more powerful PDHc El inhibitors with effective herbicidal activity, all substituents R, R, R, R, and Yn in structure I were systemically modified. Through structural modification or optimization, more than thirty novel series of structure I including alkylphosphonates, monosalts of alkylphosphonic acids, alkylphosphinates, monosalts of alkylphosphinic acid, cycUc phosphate, and caged bicyclic phosphates were designed and synthesized (Scheme 1.20). Their herbicidal activities were evaluated. Structure-activity relationship was then established and analyzed. Enzyme inhibition, toxicities and usage of representative compounds in this group were also stodied later. 

Several different types of cyclic phosphonates IVA-IVF were designed on the basis of the alkylphosphonates lo. Moreover, the cyclic phosphonates IVC-IVF were further modified to the caged bicyclic phosphates IVG-IVH (Scheme 1.32). It was expected that herbicidal activity of compounds could be optimized by introducing a phosphorus-containing heterocyclic moiety. 82 of cyclic phosphonates IVA-IVF and 27 of caged bicyclic phosphates IVG-IVH hence were prepared. 

Scheme 1.32 Design of cyclic phosphonates IVA-IVF and caged bicyclic phosphates IVG-IVH...

Therefore, several different types of cychc phosphonates IVA-IVF were designed on the basis of the alkylphosphonates lo. Moreover, the cyclic phosphonates were modified to the caged bicyclic phosphates IVG-IVH (Scheme 5.1). 

In this chapter, we focus on the synthesis, herbicidal activity, and stmcture-activity relationship of cyclic phosphonates IVA-IVF, and caged bicyclic phosphates IVG-IVH. Indeed, the bioassay results showed that several cyclic phosphonates exhibited promising herbicidal activity and potential utility as herbicides. 

Heterocyclic compounds containing a symmetric caged bicyclic phosphate have received much attention since they were first synthesized by Verkade and Re3molds in 1960 [51]. Several of these compounds with useful biological activity had been reported [52-64]. 

In the series of IVG, further modification was focused on substituent Y . On the basis of caged bicyclic phosphate IVG, substituted phenoxyacetyl moiety in IVG was modified into substimted phenox3 propionyl moiety to produce a series of IVH. In the series of IVH, O or S as X was kept constant respectively, further modification was focused on substituent Y . 

Caged bicyclic phosphates IVG were synthesized by the condensation of substituted phenoxyacetyl chlorides M5 and 4-(hydroxymethyl)-2,6,7-trioxa-l-phosp-habicyclo[2.2.2]octane-l-one M21 in the presence of base (Scheme 5.9). Substituted phenoxyacetic acids M4 and substimted phenoxyacetyl chlorides MS were prepared using the method which has been described in Chap. 2. The intermediate M21 could be prepared by the treatment of the pentaerythritol with 1 equiv. of phosphorus oxychloride in dioxane according to the method reported in the literature [65]. Caged bicyclic phosphates IVG were found to be easily regenerated... 

Since a carboxylic acid ester bond which is sensitive to acid, base or water, is contained in caged bicyclic phosphate IVG and IVH, this synthetic reaction required moderate temperamre and weak base. Reagents and solvents needed to be preprocessed in anhydrous state. 

In the H NMR spectra of caged bicyclic phosphates FVH, the chemical shifts of aromatic protons appeared at 6.8-7.5 ppm, generally. Six proton signals corresponding to three methylene groups on the bicyclic ring appeared at 4.5 ppm as a... 

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