978. Organophosphorus compounds of sulphur and selenium. Part XXII. Reactions of organic disulphides with dialkyl phosphites and thiophosphites

Synthesis of phosphorothioates using thiophosphate salts

“…As a part of our efforts to explore the utility of surface-mediated reactions for the synthesis of organophosphorus compounds, [ 16 - 18 ] herein we report a new method for the preparation of phosphorothioates by reaction of diethyl phosphite with alkyl halides in the presence of a mixture of triethylamine/sulfur/alumina under solvent-free conditions using microwave irradiation. We found that a mixture of alumina, sulfur, diethylphosphite and triethylamine under microwave irradiation gave triethylammonium O,O '-diethyl thiophosphate that can be used for the synthesis of phosphorothioates under solvent free conditions (Scheme 7 , Table 1 ).…”

“…[ 9 - 12 ] Despite their wide range of pharmacological activity, industrial and synthetic applications, the synthesis of phosphorothioates has received little attention. The following methods, not generally applicable, have been reported in the literature: (i) reaction of dialkyl phosphites with sulfenyl chlorides,[ 13 ] sulfenyl cyanides,[ 14 ] thiosulfonates,[ 15 , 16 ] disulfides,[ 17 ] and sulfur, [ 18 - 21 ] (ii) condensation of phosphorchloridate with thiols [ 22 - 26 ] and (iii) redox-type reactions of phosphorus triesters with thiols in the presence of tellurium (IV) chloride. [ 27 , 28 ] However, all of these methods have problems, including drastic reaction conditions and also some severe side reactions.…”

A Convenient Synthesis of Phosphorodithioates and Novel Conversion of Epoxides to Thiiranes

“…8,9 Despite their wide range of pharmacological activity, industrial and synthetic applications, the synthesis of phosphorodithioates has received little attention. The following methods, not generally applicable, have been reported in the literature: (i) reaction of alkali salts of dialkyl phosphorodithioic acids with alkyl halides or their addition to double bonds 10 (ii) reaction of thiol salts with dialkyl phosphorochlorododithioate 11 (iii) reaction of disulfides of dialkyl phosphorodithioic acids with Grignard reagents or alkyl or aryl lithium reagents 12 and (iv) oxidative coupling of H-phophonodithioates with alcohols in the presence iodine in pyridine. 13 However, all of these methods have problems as include drastic reaction conditions, expensive reagents and starting materials, and a longer reac-tion time in the first method leads to a competitive reaction as shown in Scheme 1.…”