3-Phosphorylated thioazoles

A novel procedure is reported for the synthesis of 3-phosphorylated N,S-heterocyclic systems by regio- and chemoselective reaction of chloroethynylphosphonates with the thio tautomers of various thioazoles. If the initial sulfanyl azole possesses labile protons or basic NR groups, partial or complete loss of chemoselectivity is observed, and the products are the corresponding acyclic 1,2- and 2,2-substituted alkenylphosphonates.