Some Features of Phosphorylation of 4-Substituted Thiosemicarbazides with Chloroethynylphosphonates

The reactions of chloroethynylphosphonates with 4-substituted thiosemicarbazides leads to the predominant formation of dialkyl esters of 5-substituted (1,3,4-thiadiazol-2-yl)methylphosphonic acids with an admixture (up to 31%) of dialkyl [3-amino-2-(alkylimino)-2,3-dihydro-1,3-thiazol-4-yl)phosphonates as a minor product.