Phosphinothioates Phosphinodithioates

Both (R)-(-t-)- and (S)-(-)-tertiarybutylphenylphosphine sulphides (6) have been synthesised in high optical purity from (S)-(-)- and (R)-(+)-tertiarybutylphosphinothioic acids, respectively, by formation of the mixed anhydride (5) followed by borohydride reduction (Scheme 2). Reactions of the product (6) have been used to provide routes to optically active phosphinothioic iodides, phosphinodithioates and thioselenophosphinic acids of known configurations. A new method for the asymmetric synthesis of tertiary phosphine oxides has been reported.5 An Arbusov reaction of the optically active 1,3,2-... 

Phosphinodithioic acids, R2P(S)SH, (9.433a) can be made in up to 90% yields by the action of secondary phosphines on sulphur in dilnte ammonia. The ammonium salts so obtained can then be converted into the corresponding acids with HCl (9.434). Phosphinodithioic adds can in some instances be obtained from phosphinothioic halides and sodium hydrosulphide (9.435). They may also be made by a Friedel-Crafts-type reaction with benzene (9.436). Metal salts may be produced directly by the action of sulphur and alkali sulphide, or sulphur and metal, on diphosphine disulphides (Figure 9.23). 

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