A series of novel dimethyl 7-((2S,3S)-3-((1-(4-chlorophenyl)-1H-1,2,3-triazol-4-yl)methoxy)-3,6-dihydro-2H-pyran-2-yl)-4-(4-fluorophenyl)-9-oxo-8-phenyl-6-thia-1,2,8-triazaspiro[4.4]non-2-en-3-ylphosphonate 11a-g have been synthesized by the reaction of chalcone derivatives of (E)-5-benzylidene-2-((2S,3S)-3-((1-(4-chlorophenyl)-1H-1,2,3-triazol-4-yl)methoxy)-3,6-dihydro-2H-pyran-2-yl)-3-phenylthiazolidin-4-one 10a-g with Bestmen Ohira reagent. The chemical structures of newly synthesized compounds have been elucidated by IR, NMR, MS and elemental analysis. The compounds 11a-g have been evaluated for their nematicidal activity against Dietylenchus myceliophagus and Caenorhabditis elegans. Compound 11b, 11c, 11g and 11f show appreciable nematicidal activity.