Preparations of thiophosphites and thiophosphonates

Abstract

Improved methods for converting phosphite or phosphonate esters into corresponding thiophosphites or thiophosphonates and for synthesizing specific thiophosphite and thiophosphonate compounds so produced are disclosed and claimed. The methods start from phosphite diesters using P.sub.4 S.sub.10 as the thionation reagent. The reaction mixture is refluxed until the reaction is complete and may be followed by separation and chloroformate ester phosphonation steps to produce pure thiophosphonocarboxylate triesters. Alternatively, these esters may be prepared directly by action of P.sub.4 S.sub.10 on the corresponding phosphonocarboxylate esters. The former method was used to prepare dimethyl thiophosphite and thence trimethyl thiophosphonoformate, a key intermediate in synthesis of salts of thiophosphonoformic acid, which have anti-viral properties.

Dependencies are inferred from the claim text.