Phosphates and Thiophosphates

Aryl phosphates and thiophosphates, and alkyl dithiophosphates are important agrochemicals, while phosphorofluoridates have been prepared as chemical warfare agents. Concern over the persistence and the biodegradability of organophosphate and organophosphorothioates, which are nsed as agrochemicals, has stimnlated stndies into their degradation. Considerable attention has been... 

Information concerning inositol phosphates and thiophosphates is included in the review by Potter[41]. 

When trying to understand the reactivity of phosphate and thiophosphate esters, it is important to realize that such compounds may react like alkyl halides by nucleo-... 

Phosphoric acid chloride and thiophosphoric acid chloride pyrididium betaines (I) which are easily prepared by reacting P401Qt P OgS. and P4S1Q, respectively, with phosphorus oxychldride or phdspnorus thio-chloride in the presence of pyridine (1.), are of interest for the synthesis of substituted phosphates and thiophosphates. 

N Reactions of the betaines I with initial cleavage of the P-N bond (type B) are rarely observed. One example is the reaction with hydrogen halides leading to dihalogeno phosphates and -thiophosphates ... 

The chemistry of boron-phosphorus compouuds has been reviewed. Numerous boron-phosphorus derivatives have been reported, but relatively few boron-arsenic or boron-antimony compounds have been described. Boron-phosphorus compounds are similar in many ways to boron nitrogen derivatives, but the teudeucy to share boudiug electrons in covalent tetrahedral compounds is much more evident with phosphorus thau with uitrogeu. lu fact, most boron phosphorus chemistry iuvolves tetrahedral borou. They are typically either phosphiue-boraue complexes, such as R3P BR j, or phosphinoboranes (R2PBR2) , cyclic or polymeric derivatives of the hypothetical H3P BH3. The chemistry of these compounds and that of boron phosphate and thiophosphate is described below. Boron phosphides are discussed in Section 2.6. 

Diferrocenyldithiadiphosphetane disulfide (95) has been reported to react with bicyclic dienes to form four- and six-membered phosphorus and sulfur-containing rings which are characterised by X-ray crystallography in several cases. Phosphate and thiophosphate triesters react with a-diazoacetates in the presence of BFa.etherate as a catalyst to give, respectively, O-alkoxycarbonylmethyl phosphates 96 and S-alkoxycarbonylmethyl phosphates. ... 

A number of phosphate and thiophosphate esters are of limited thermal stability and undergo highly exothemiic self-accelerating decomposition reactions which may be further catalysed by impurities. The potential hazards can be reduced by appropriate thermal control measures. An example is the substitution of hot water at 60 C for pressurised steam to melt a solid phosphate ester, which on adiabatic calorimetric examination was found to have a time to maximum decomposition rate of 6 h at 110° but 11 h at lOO C [2]. The combined use of vapour phase pyrolysis to decompose various phosphoms esters, and of GLC and mass spectrometry to analyse the pyrolysis products, allowed a thermal degradation scheme to be developed for phosphorus esters [3]. Individually indexed compounds are ... 

The barrier to inversion about phosphorus in phosphites is large enough for tricovalent phosphites chiral at phosphorus to be configurationally stable, but the conditions for the coupling of phosphoramidites epimerised them at P about 10 times faster than it coupled them, although the oxidation of phosphites to phosphates and thiophosphates proceeded with complete retention of phosphorus stereochemistry. ... 

Substantial numbers of important agrochemicals contain the carbonyl groups noted earlier, so that abiotic hydrolysis may be the primary reaction in their transformation the example of carbaryl has already been cited (Wolfe et al. 1978a). The same general principles may be extended to phosphate and thiophosphate esters, although in these cases, it is important to bear in mind the stability to hydrolysis of primary and secondary phosphate esters under neutral or alkaline conditions that prevail in most natural ecosystems. On the... 

Methods for Syntheses and Configurational Analyses of Oxygen Chiral Phosphate and Thiophosphate Esters... 

There has been a continuing high level of activity directed towards the synthesis of phosphates and thiophosphates derived from myo-inositol. Phosphorylation (POCl or PSCl s pyridine) of DL-1,2,4,5,6-penta-O-acetyl-myo-inositol has yielded,... 

There are several indications, mainly in the patent literature, of possible uses of tetrahydroquinoxalines. Derivatives related in structure to Hetrazan (l-diethylcarbamoyl-4-methylpiperazine) have been prepared as potential drugs for the treatment of filarial infections. Other tetrahydroquinoxalines of type 43 have been screened for antineoplastic activity and bisindolyl derivatives of type 44 have been claimed to have a wide spectrum of biological activity. Tetrahydroquinoxaline phosphates and thiophosphates have been patented as insecticides, and other tetrahydroquinoxalines have been patented for protecting rubber against... 

The rearrangement of dialkyl 3-pyridinyl phosphates and thiophosphates under the influence of a base (Ida) at low temperatures has been shown to be remarkably regioselective. In the case of the diethyl phosphate ester, the sole product is diethyl (2-hydroxy-4-pyridinyl)phosphonate with the corresponding thiophosphate O, O, (9-triester, diethyl (3-hydroxy-2-pyridinyl)phosphonothioate is formed in a large excess over the (2-hydroxy-4-pyridinyl)phosphonothioic diester ... 

The conformational barrier for 1,3,2-dioxaphosphorinanes is somewhat greater, although many six-membered phosphates and thiophosphates have been shown to be in equilibrium with twist conformations in solution. The activation energy for chairs twist interconversion of the cyclic nucleotide derivative phenoxy-cTMP [81] has been estimated to be only 2.2kcalmol (this value is proposed as an upper limit) (Nelson et al., 1987). 

As in the case of adenylate cyclase, the application of chiral phosphate and thiophosphate analysis techniques has yielded the most definitive evidence on the enzymic mechanism of cAMP phosphodiesterase. Eckstein and coworkers were able to determine the stereochemistry of the reaction of cAMP phosphodiesterase from beef heart using the phosphorothioate cAMP(S) substrate (Burgers et al., 1979b). This approach had been made possible by the development of the diastereomers of cAMP(S) by Stec (Baraniak et al., 1979). Phosphodiesterase-catalysed hydrolysis was carried... 

Further developments in the. synthesis of phosphate and thiophosphate esters from myo-inositol (10) have been widely described. By and large, these syntheses have followed the procedures and used reagents (particularly with regard to the nature of protection... 

HCl in dichloromethane or acetone has been used to cleave isopropylidene and benzylidene acetals in the presence of other acid-sensitive groups. Iso-propylidene-protected sugar phosphates and thiophosphates, such as 11, were deacetalated by heating in water without added acid, the aq. solutions having a... 

With phosphates and thiophosphates LiMnPO 300- -35 5.95 + 85 vib. 6>n = 35 K determined from Curie-Weiss law 67S8, Fig. 130... 

The proposed differential energetic effects on transferring the ground State and the transition state for hydrolyzing phosphate and thiophosphates monoester dianions from water to DMSO was tested by Hengge s group... 

Fig. 3. VpocH versus PCX H dihedral angles in phosphites (O, ) and phosphates and thiophosphates (0 - ). See White and Verkade (1970) for structures. Dashed curve from Kainosho and Nakamura (1969).

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