Thiophosphate intermediate

Presumably intermediate thiophosphoric acids are first formed and, indeed, when the hydrolysis is carried out in aqueous NaOH solution at 100°, substantial amounts of the mono- and di-thiophosphates are obtained. P-S bonds are also retained during reaction of P4S10 with alcohols or phenols and the products formed are used extensively in industry for a wide variety of... 

Titanium(III) chloride (particularly in slightly alkaline medium) reduces the p-nitro groups of the thiophosphate insecticides to amino groups, which are then reacted with nitrite in acid mediiun in a second step to yield a diazonium compound as intermediate. This is then coupled to N-(l-naphthyl)-ethylenediamine dihydrochloride to yield an azo dye [3]. In the case of benzodiazepines the first reaction step includes an additional acid hydrolysis to the corresponding benzophenone derivative [2]. 

The resulting products, such as sulfenic acid or sulfur dioxide, are reactive and induce an acid-catalyzed breakdown of hydroperoxides. The important role of intermediate molecular sulfur has been reported [68-72]. Zinc (or other metal) forms a precipitate composed of ZnO and ZnS04. The decomposition of ROOH by dialkyl thiophosphates is an autocata-lytic process. The interaction of ROOH with zinc dialkyl thiophosphate gives rise to free radicals, due to which this reaction accelerates oxidation of hydrocarbons, excites CL during oxidation of ethylbenzene, and intensifies the consumption of acceptors, e.g., stable nitroxyl radicals [68], The induction period is often absent because of the rapid formation of intermediates, and the kinetics of decomposition is described by a simple bimolecular kinetic equation... 

The phosphoranes, e.g. (69), which are intermediates in the Arbusov reactions of the cyclic phosphite (68) with chlorine, bromine, and benzenesulphenyl chloride have been detected at low temperatures by 31P n.m.r. spectroscopy.47 A similar technique revealed the intermediate (71) in the reaction of the thiophosphate (70) with chlorine.48... 

There are few potent competitive inhibitors for alkaline phosphatase (Table VII) (4, 21, 94, 96, 100, 105-109). Phosphate, thiophosphate, and arsenate have low values for KThese substances are actually substrates and can form a covalent intermediate. However, this is probably not the reason why they are potent inhibitors since in the case of phosphate the Michaelis complex is more stable than the covalent intermediate (30). The values of Kt for phosphate and arsenate at various pH values have been published (SO, 106, 110). 

There is evidence (but not conclusive evidence) that the mechanisms involves direct phosphoryl transfer to water rather than the formation of a phosphoenzyme intermediate.293 This utilizes the fact that ATP also serves as a substrate to inorganic pyrophosphatase. Hydrolysis of the ATP analogue adenosine 5 -0-(3-thiotriphosphate) chirally labelled with I70 and I80 at the y-phosphate proceeds with inversion of configuration to give the chiral [170,180]-thiophosphate (Figure 13).293... 

Synthesis of oil soluble micellar calcium thiophosphate was performed in a one-step process involving the reaction of calcium oxide, tetraphosphorus decasulfide and water in the presence of an alkylaryl sulfonic acid. This product could be defined as a calcium thiophosphate hard-core surrounded by a calcium alkylarylsulphonate shell in accordance with a reverse micelle type association in oil. Three micellar products with the same chemical nature core were prepared, each with different core/shell ratio of 0.44, 0.92 and 1.54. Better performances are expected with products of higher core/shell ratios. The antiwear performance of micellar calcium carbonates is directly linked to the size of the mineral CaC03 colloidal particles. At a concentration of 2 % micellar cores, no antiwear effect is observed whatever the micellar size. At an intermediate concentration of 4 % of micellar cores, the wear scar diameter is clearly dependent on the micellar size, slipping from 1.70 mm to 1.10 mm, then to 0.79 mm when the core diameter moves from 4.37 nm to 6.07 nm, then to 6.78 nm. Size dependence is increased at a concentration of 5 % in colloidal cores. This clearly confirms the size dependence of the micellar cores on their antiwear performance (Delfort et al.,... 

The absolute configuration of thiophosphate indicates that inversion at phosphorus has occurred in the reaction catalyzed by ATP synthase. This result is consistent with an in-line phosphoryl transfer reaction taking place in a single step. The retention of configuration in the Ca2+-ATPase reaction points to two phosphoryl transfer reactions—inversion by the first and a return to the starting configuration by the second. The Ca2+-ATPase reaction proceeds by a phosphorylated enzyme intermediate. 

Further examples of the applications of thiophosphates in organic synthesis have been reported. The methodology based on intermediate thiophosphates (138) constitutes a general and convenient route to a wide range of conjugated non-linear trienynes (139). Thiophosphate (138) reacts readily with sodium derivative of dienynes to form (139) in one operation via single and double carbon-carbon bond formation (Scheme 41). ... 

Several new thiophosphates (140) have been prepared. They are useful precursors of novel cyclic compounds (141) which have similar structures to Baylis-Hillman adducts. The synthetic approach to these compounds involves reduction of the carbonyl group by NaBH4 in the presence of methyl iodide which exhibit full axial selectivity. Subsequent oxidation of intermediate sulphides (142) to sulphoxides (143) and cis elimination of the latter affords the desired compounds (141) of defined stereochemistry (Scheme 42). Multifunctionality of the compounds makes them attractive for numerous further important transformations. ... 

Nucleophilic attack by this species at the a-carbon atom will also be governed by the same steric considerations as in thermal decomposition and hence the inverse relationship of thermal stability and resistance to nucleophilic attack, and anti-wear activity and ease of nucleophilic attack. Further thermal processes involve olefin elimination from alkyl groups and lead to the formation of phosphorus acids. Nucleophilic substitutions of one phosphorus species by another leads to P-O-P structures and zinc mercaptide Zn(SR)2 as a reaction intermediate. Reaction of this mercaptide with dithiophosphate leads to trithiophosphates and eventually tetrathiophosphates. Finally, an oil-insoluble deposit is formed of a mixture of zinc thiophosphate and zinc pyro- and polypyrothiophosphates. 

Scheme 15 illustrates the asymmetric hydrogenation of 3-keto phosphonates catalyzed by a BINAP-Ru complex, giving P-hydroxy phosphonates in up to 99% ee [61]. The sense of enantioface differentiation is the same as that of hydrogenation of P-keto carboxylic esters (see table of Scheme 3). The reactivity of the phosphonates is much higher than that of the carboxylic esters so that the hydrogenation proceeds even at 1 to 4 atm of hydrogen and at room temperature. A Ru complex of BDPP also shows high enantioselectivity [46b]. Chiral P-hydroxy phosphonates thus obtained are useful intermediates for the syntheses of phosphonic acid-based antibiotics as well as haptens of catalytic antibodies. Similarly, P-keto thiophosphates are hydrogenated enantioselectively with a MeO-BIPHEP-Ru catalyst [61b].

These comparative studies constituted the first example of an enzyme-catalyzed hydrolysis reaction whose stereochemical course was unaffected by sulfur substitution. At the time these experiments were performed, the stereochemical courses of the reactions catalyzed by glycerol kinase (83, 84) and by the bacterial adenylate cyclase (85, 86) had already been compared in the laboratories of Knowles and Gerlt, respectively, and these were also found to be unaffected by the sulfur substitution. A number of other comparisons of this type have been made, and in no case were the stereochemical consequences of the reactions studied with chiral phosphate esters and the chiral thiophosphate analogs found to differ. This agreement suggests that the necessary use of oxygen chiral thiophosphate monoesters to study the stereochemical course of phospho-monoesterases will provide pertinent results for ascertaining whether phosphory-lated intermediates are involved in the reaction mechanism. 

Nucleophilic replacement of a 5-bromo by an isothiourea group and careful alkaline hydrolysis of the resulting 5-alkylthiouronium salt is a method of preparing l,2,4-thiadiazole-5-thione unsubstituted in its 3-position. An alternative procedure314 is the successive treatment of 5-chloro-1,2,4-thiadiazoles with trisodium thiophosphate, and add-catalyzed decomposition of the intermediate salt [HetSPO(ONa)2] in situ 15 5-Chloro-l,2,4-thiadiazoles are also a useful source of 5-alkyl and -aryl sulfones and 5-alkyl and -aryl thiols these are readily obtainable by the action of the appropriate sodium sulfinates or thiols.316-318 The action of... 

S)- 0, 0]-thiophosphoenolpyruvate, generated in situ from 2-[(5)- 0, 0]-thiophospho-D-glycerate in the presence of enolase, has been used as a substrate in the phosphoenolpyruvate carboxylase reaction carried out in [ 0]-labelled water. From the absolute configuration of the [ 0, 0/ 0]-thiophosphate produced, it was deduced that this reaction proceeds by a stepwise mechanism involving the intermediate formation of carboxyphosphate (Scheme 2). This deduction is, however, at variance with a mechanism proposed on... 

When a concentrated solution of ( p)-(2-hydroxymethyl-4-nitrophenyl) [ 0, 0]thiophosphate (147) of at least 95 e.e. was rapidly diluted with rm-butyl alcohol, there resulted a mixture of comparable amounts of (148) and (149)/(150). The rm-butyl ester (148) was present in racemic form thus confirming a contribution from the full dissociation of (147) into a free monomeric thiometaphosphate intermediate. The composition of the (149)/(150) mixture, indicating roughly 60% racemization with 40%... 

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