Direct α-chlorination of O,O-dialkyl chalcogenophosphonates with phosphorus oxychloride

α-Chlorination of phosphonates, and O,O-dialkyl thio- and selenophosphonates involving the direct reaction of their lithiated anion with phosphorus oxychloride is described. The reaction gives good results where previously known methods fail. The role of the chalcogen atom, and the influence of the nature of the alkyl chain with respect to the reactivity are discussed.