Ester organophosphorus, reaction with

There are several examples in the literature of activation of hydroxy compounds by various organophosphorus compounds. For example, in the presence of pyridine, ji-butyltriphenoxyphosphonium bromide (1) activates carboxylic acids towards reaction with amines or phenols to give, respectively, amides or esters (1). 

The Wittig reaction and its numerous derivations have undoubtedly proven to be one of the most useful and efficient methods for forming carbon-carbon double bonds . The reaction of an organophosphorus reagent with an aldehyde or ketone has also been frequently employed to extend simple dienals and dienones into more elaborate polyene systems. A key step in the convergent synthesis of the TB DMS-protected leukotriene A4 methyl ester, 19/ ,5 -Z-butyldimethylsiloxy-5S, 6S -epoxyeicosa-7 ,9 , 1IZ, 14Z-tetraenoate (43), was accomplished using a Wittig reaction between homoallylic phosphorus ylide 44 and Cl—Cll chiral epoxy dienal 45, derived from (—)-2-deoxy-D-ribose, shown in equation 29. ... 

Diaryl methyl- and benzyl-phosphonates are conveniently prepared in high yields by heating mixtures of triaryl phosphites, methanol or benzyl alcohol, and a trace of methyl or benzyl halide. In a reaction that is usefully complementary to the previously reported formation of pyridine-2-phosphonic acid derivatives from sodium dialkyl phosphonates and //-methoxypyridinium compounds ( Organophosphorus Chemistry , Vol. 7, p. 111), N-triphenylmethylpyridinium tetrafluoroborate affords the pyridine-4-phosphonic dialkyl ester when heated with sodium dialkyl phosphonates. ... 

A3. Abou-Donia, M. B., and Lapadula, D. M., Mechanisms of organophosphorus ester-induced delayed neurotoxicity Type I and Type II. Ann. Rev. Toxicol. 30,405-440 (1990). A4. Aldridge, W. N., Organophosphorus compounds and carbamates, and their reactions with esterases. Brit. Med. Bull. 25, 236-239 (1969). 

The addition of isocyanides and azide to aldehyde-derived enamines has led to tetrazoles (533,536). On the other hand the vinylogous amide of acetoacetic ester and related compounds reacted with aldehydes, isocyanides and acids to give a-acylaminoamides (534). Iminopyrrolidones and imino-thiopyrrolidones were obtained from the addition of cyclohexylisocyanide and isocyanates or isothiocyanates to enamines (535). An interesting method for the formation of organophosphorus compounds is found in the reactions of imonium salts with dialkylphosphites (536). 

In contrast to the reactions of the cycloamyloses with esters of carboxylic acids and organophosphorus compounds, the rate of an organic reaction may, in some cases, be modified simply by inclusion of the reactant within the cycloamylose cavity. Noncovalent catalysis may be attributed to either (1) a microsolvent effect derived from the relatively apolar properties of the microscopic cycloamylose cavity or (2) a conformational effect derived from the geometrical requirements of the inclusion process. Kinetically, noncovalent catalysis may be characterized in the same way as covalent catalysis that is, /c2 once again represents the rate of all productive processes that occur within the inclusion complex, and Kd represents the equilibrium constant for dissociation of the complex. 

Inmost instances, a haloorganic subject to either SN2 displacement reaction or SN1 substitution is heated at reflux with the trivalent phosphorus ester with the concomitant formation of the valence-expanded organophosphorus compound and haloorganic by-product, as illustrated with an example in Equation 3.1. 

Reaction of Sodium Perborate with Organophosphorus Esters... 

Studies of the in vitro reaction between the alkaline oximes and sarin (isopropyl methylphosphonofluoridate, GB) revealed that 2-PAM reacted rapidly with the organophosphorus ester in solution at physiologic pH and temperature (Figure 2-2)... 

The reaction of phosphonic acid chloride (254) with (S)-proline ethyl ester afforded a mixture of diasteromeric amides (255) in high diastereoselectivity. The diastereomers (255) can easily be purified by chromatography. The chiral, practically optical pure organophosphorus compound (256) was obtained from purified (255) by acid alcoholysis. 

A noteworthy synthetic application for the reaction of J with a,g-unsaturated phosphoryl compounds is represented by the addition involving hitherto unknown (-)-(Sp)-methylphenylvinylphosphine oxide J 2. The resulting tertiary phosphine oxides 13 with saturated carbon chains and known stereochemistry at phosphorus constitute attractive starting materials for the preparation of optically pure phosphines. The organophosphorus substrate 12 was obtained by decarbomenthoxylation of the enantiomeric ester... 

Table II. Rate Constants for Reaction of Organophosphorus Esters with Sodium Methoxide (0.116M) in Methanol at 20.0°.

We have studied the reaction of methyl trifluoromethanesul-fonate (methyl triflate) with isopropyl methylphosphinate (1), and have used this system to develop a new procedure for the stereospecific synthesis of trivalent (P ) organophosphorus esters. 

The structure of the organophosphorus compound has a considerable effect on the direction of the reaction. Thus, whereas the yield of phosphorus-containing 3-ethenyl-2-indolinones 149 in the case of phosphorylacetic esters amounted to 36-38%, with phosphorylacetone it was possible to isolate 46-48% of the target compounds, but here the process was accompanied by P,0-olefination. 

The O-dealkylation of organophosphorus triesters differs from the above reactions in that it involves the dealkylation of an ester rather than an ether. The reaction was first described for the insecticide chlorfenvinphos (Figure 10.2B), but is now known to occur with a wide variety of vinyl, phenyl, phenylvinyl, and naphthyl phosphates and the thionophosphate triesters. At least one phosphonate, O-ethyl O-p-nitrophenyl phenylphosphonate (EPNO), is also metabolized by this mechanism. 

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