Phosphinothioic acids reactions

The reaction of carbodiimides with phosphonothioic and phosphinothioic acid as well as phosphonoselenoic and phosphinoselenoic acids " proceed in a similar manner. 

The interaction of a phosphinothioic acid (or a dialkyl phosphorothioic acid) with an alkyl isocyanide yields the corresponding A-alkylthioformamide together with a monothio anhydride (reaction 21) ". A further interesting sequence commences with the interaction of a diarylphosphine oxide, R2P(0)H (R = Ph or p-Tol) with HCNS. It is known that such... 

The mono-thio, -seleno and -telluro analogues of phosphonic and phosphinic acids are tautomeric (equations 1, 2 and 4). In the case of the sulphur-containing compounds, an attempt has been made to estimate the equilibrium compositions of a variety of acids by means of physicochemical measurements. The alkali metal salts of phosphonothioate and phosphinothioate acids possess anions which are mesomeric and, theoretically, it is possible for such ions to act as sources of both O-and S-substituted products. The same products can be obtained through reactions between the free acids and diazoalkanes, and because these reactions are relatively fast, it might be expected that the composition of the product mixtures might be a reflection of the tautomer composition of the acids. 

The alkylation, with the more reactive of alkyl halides, of the sodium salts of monoes-terified phosphonothioic acids (equation 22) (see also Scheme 11) or of the disodium salts 107 results in preferential S-alkylation, and the same situation obtains for the salts of phosphinothioic acid " methylation can also be carried out with dimethyl sulphate. Alkylations may also be performed under phase-transfer conditions. From both practical and theoretical perspectives, the subject is more complex, since the course of alkylation reactions depends on the nature of the alkylating agent, on the polarity of solvent and whether this is protic or non-protic and on the concentrations of reactants a study of these features has been the subject of two reports In non-polar or weakly polar aprotic media, or in EtOH, alkylation occurs almost exclusively on sulphur, but in dipolar aprotic solvents, O-alkylation also takes place. The relative yields of sulphur- and oxygen-substituted derivatives, [Qs/Qol depends, for a given solvent, on the nature of substituents on phosphorus, i.e. essentially, whether the substrate is a thiophosphoric, thiophosphonic or thiophosphinic acid. With alkyl tosylates as alkylating agents at 0.02 m in hmpt, the alkylation of sodium 0,0-dialkyl or diphenyl phosphorothioates results in 100% overall conversions with [Qs/Qo] 5 the overall yields for sodium diphenyl- or diisopropyl-phosphinothioates are lower (50-100%) with [Qs/Qo] 1 ... 

The effects of changes in structure, temperature, and reaction medium on the kinetics of alkaline hydrolysis of aryl esters of phosphinothioic acids (182 R = R = Me or Ph R = Me, R = Ph X = H, Br, Me, or NO2) have been investigated. The effect of the nature of the leaving group on the kinetics of alkaline hydrolysis of aryl diphenylphosphinates has also been reported on. Indirect evidence has been advanced for the participation of the azaphospholi-dines (183) in the solvolysis of A/-[amino(methyl)phosphinyl]-L-phenylalanine derivatives, and it includes the transfer of the P-amino group to the phenyl-alanyl carbonyl. The products from the hydrolysis or ammonolysis of fosfomycin have the threo structure and have been shown to possess no antibiotic activity. ... 

The deselenonation of phosphinoselenoic acids by dimethyl sulfoxide (DMSO) (39) proceeds exothermically, whereas the corresponding reaction with phosphinothioic acids requires heating at 100°. The reactivity of the P=X bond is proportional to the softness disparity of the two adjoining atoms. 

Reaction of optically pure 104 with organolithiums to form 105 occurs with preponderant P-0 bond cleavage and retention of configuration (de>90%), exactly like in the modern Juge-Stephan method, but at that time those observations were unexpected. The retention of configuration in the ring opening of 104 was explained by the sequence formation of a pentacoordinated intermediate-pseudorotation-apical elimination. Acidolysis of 105 produced the desired phosphinothioic acids 106 in ee values better than 90%. This step is also directly comparable to the acidic methanolysis in the modern method. 

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-... 

The stereochemistry of the reaction of phosphinate esters with organo-metallic derivatives has been reviewed. Oxidation of the phosphinothioate ester (105) to the P=0 analogue with /n-chloroperoxybenzoic acid has been shown to proceed with > 90% retention of configuration, whereas under the... 

When diphenylphosphinodithioic acid is heated at 170 °C for an extended period, a loss of H2S occurs with the formation of the anhydrosulphide. Related compounds are also easily prepared by the reactions between salts of dithioic acids (these are more reactive than salts of phosphinic acids) and phosphinothioic halides obviously, this procedure is capable, in principle, of providing unsymmetrical anhydrosulphides (equation 46), but these tend to disproportionate into a mixture of symmetrical compounds ... 

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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