Cyclic 1-Hydroxyalkylphosphonates IVA and IVB

1 -Hydroxyalkylphosphonates as a kind of active compound or important intermediate have received much attention [24—26]. Some of them were widely used as biophosphate mimics [27], enzyme inhibitors [28,29] antibacterial agents [30, 31] antiviral agents [32], anti-cancer and antitumor agents [33, 34] anti-HIV agents [35, 36] and haptens for catalytic antibodies [37]. In addition, 1-hydroxyalkylphosphonates also served as an attractive precursor in the synthesis of various 1-substituted alkylphosphonates [38 0]. 

As stated in Chap. 2, several series of open-chain 0,0-dialkyl 1-hydrox-yalkylphosphonates M2 have been prepared and studied. In order to examine the herbicidal activity of phosphorus-containing heterocyclic 1-hydroxyalkylphosph-onate and their derivatives, firstly two series of cyclic 1-hydroxyalkylphosphonates including 2-(l-hydroxyalkyl)-5,5-dimethyl-4-pheny-l,3,2-dioxaphosphinane-2-ones IVA and 2-(l-hydroxyalkyl)-5,5-dimethyl-l,3,2-dioxaphosphinane-2-ones IVB were synthesized. 

In the IVA and IVB series, further modification was focused on substituent R. In this section, we describe the synthesis and herbicidal activity of cyclic 1-hydroxyalkylphosphonates, IVA and IVB. The results of preliminary bioassay indicated that IVA and IVB exhibited certain herbicidal activity. 

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Cyclic 1-hydroxyalkylphosphonates IVA and IVB could be synthesized by Pudovik reaction (Scheme 5.2) [41]. Cyclic 1-hydroxyalkylphosphonates IVA were prepared by hydrophosphonylation of various aldehydes with 5,5-dimethyM-phenyl-l,3, 2-dioxaphosphinane-2-one M18-1 in the presence of triethylamine as a basic catalyst. The cyclic phosphonate M18-1 could be easily prepared by the reaction of... 

Detailed synthetic procedures for cyclic 1-hydroxyalkylphosphonates IVA and IVB are introduced in the Sect. 9.1.23 of Chap. 9. The structures of IVA and IVB were established by well-defined IR, NMR, and elemental analysis. IVA-3 (R = 4-ClPh) was further analyzed by X-ray single-crystal difliraction. Spectroscopic analyses of some representative IVA and IVB are given in Sect. 5.1.3. 

Compared with clacyfos (IC-22, HW02), IVD-12 exhibited a shghtly higher herbicidal effect against broad-leaved weeds, leaf mustard or common amaranth, and also showed much higher herbicidal activity against monocot weeds than that of clacyfos. However, cyclic 1-hydroxyalkylphosphonates IVA and IVB had no significant herbicidal activity (Sect. 5.1.5). All cyclic phosphonates IVC were also not comparable to clacyfos. 

Cyclic 1-hydroxyalkylphosphonates IVA and IVB could be synthesized by hy-drophosphonylation of various aldehydes with cyclic phosphonates M18 in the presence of triethylamine as a basic catalyst (Scheme 9.23). 

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