Deoxygenation and Desulphurization Reactions

Dialkyl thiosulphonates (37) are desulphurized by tris(diethylamino)phos-phine to give sulphoxides. In some cases sulphinate esters are formed as minor products. Diaryl thiosulphonates gave 1 1-adducts of the type (38). Desulphurization of sulphenimides (39) by tris(dimethylaniino)phos- 

Desulphurization of the disulphide (44) has been shown to result in epimerization at the asymmetric carbon atoms. Synthetic applications of 

The reaction of dipyridyl disulphide with triphenylphosphine to give the stable phosphonium salt (51) has been used in new methods of phosphorylation (reaction A), in peptide synthesis (reaction B), and in the formation of active esters of cx-amino-acids (reaction C). These reactions appear to have synthetic potential. 

The deoxygenation of peroxycarbonates (53) with phosphines and phosphites has been examined. Reaction with phosphites favours pyrocarbonate formation (Path A) whilst phosphines favour carbonate formation (Path B). Secondary phosphine oxides are oxidized to phosphinic acids by perbenzoic acid. The kinetics of the deoxygenation of hydroperoxides by triphenylphosphine have been examined and the reaction shown to be catalysed by strong acids.  

There is a continuing interest in the use of phosphite-ozone adducts as sources of singlet oxygen and as reagents for mimicking the reactions of this species. The commercially available phosphite (54) forms an ozone adduct of striking stability. Decomposition of the adduct only becomes appreciable at temperatures 0 °C the decomposition exhibits first-order kinetics, so that at 10 °C= 9.10 x 10 min and= 76.2 min. These 

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