Acylphosphonates acidity

Dialkyl phosphites react with acyl halides such as lauroyl chloride to yield surface-active acid esters of acylphosphonic acid [84-87] see Eq. (40). 

Sekine, M. and Hata, T., Convenient synthesis of unesterified acylphosphonic acids, Chem. Commun., 285, 1978. 

Acyclic cationic systems, chalcogen-halogen compounds, 35 299-301 Acylarsonic acids, 44 217 Acyldiazenido complexes, mechanisms of formation, 27 223-225 Acylium cation, 9 231, 241-243 Acylphosphonic acids, 44 217 Acylsilane, hydrolysis, 42 173 Adamantane... 

A number of acylphosphonic acids are of interest for their biological activity, or as intermediates in syntheses of potentially bioactive phosphonic acids [7, 34, 48 - 50]. In many cases, they are most conveniently prepared by hydrolysis of the corresponding esters. Due to the presence of the keto function, acid hydrolysis (heating in aqueous HCl) is generally not a practical method to achieve this. Silyldealkylation of methyl-, ethyl- or isopropyl phosphonates with BTMS, followed by very mild hydrolysis is normally compatible with acyl and other sensitive functionalities [7,34,48]. 

Acylphosphonic acids have also been obtained by hydrolysis of di(ferf-butyl) acylphosphonates with 85% TFA [49] or by hydrogenolysis of corresponding... 

The Michaelis-Arbuzov reaction has been applied to t/7.v(trialkylsilyl) phosphites, which, on reaction with aliphatic or aromatic acyl halides in Et2O or CgHg at room temperature, undergo the rearrangement in mild conditions to produce the valuable fczXtrialkylsilyl) 1-oxoalkyl- or 1-oxoarylphosphonates in good yields (50-77%, Scheme 7.6). - Free acylphosphonic acids are obtained by treatment of the trimethylsilyl) esters with EtOH or by exposure to air for several hours. 

Treatment of acylphosphonic acids with NaBH4 in aqueous or alcoholic ammonia solution produces 1-aminoalkylphosphonic acids in good yields... 

Karaman, R., Goldblum, A., Breuer, E., and Leader, H., Acylphosphonic acids and methyl hydrogen acylphosphonates. Physical and chemical properties and theoretical calculations. J. Chem. Soc., Perkin Trans. 1, 765, 1989. 

Berlin, K.D., Hellwerge, D.M., and Nagabhushanam, M., Dialkyl esters of acylphosphonic acids,... 

Free acylphosphonic acids are easily obtained by treatment of i z.s (trimethylsilyl) (alkoxycar-bonyl)phosphonates with EtOH or by exposure to air for several hours. Diethyl (alkoxycarbo-nyl)phosphonates are prepared by condensation of the corresponding alcohols with the diethyl (chlorocarbonyl)phosphonate in the presence of EtjN or DMAP. ... 

Acylphosphonic acids (1-oxoalkylphosphonic acids) and their dialkyl esters undergo acid-catalyzed fission with the formation of carboxylic acids (or their alkyl esters) using a suiphonic acid as the catalyst the formation of an alkyl carboxylace is accompanied by that of an alkyl sulphonate. The reaction may be visualized as occurring through protonation on the carbonyl oxygen and migration of an alkoxy group from phosphorus... 

The (oxoalkyl)-phosphonic and -phosphinic acids form a remarkable group of compounds whose ease or formation, stability and versatility in use depend to a high degree on the relative positions of the oxo and phosphoryl groups. From the points of view of both synthesis and reactivity, the (1-oxoalkyl) compounds, also termed acylphosphonates, stand apart from the remaining compound types, and they have been considered separately in this volume and elsewhere the discussion here is designed to offer a comparison between syntheses of acylphosphonic acids with those of other important oxoalkyl phos-phonic and phosphinic acids. 

The field of acylphosphonates (a-ketophosphonates) has been reviewed previously This chapter will deal mostly with the advances made since the publication of the previous review however, results from the older literature will be included for completeness. This chapter includes functional derivatives of both the phosphoryl and the carbonyl groups. With regard to the phosphoryl group, this refers to acylphosphonic acids esterified to various degrees, and also to acylphosphonoamidates and to acylphosphonic mono-and dihalides. With respect to the carbonyl group, this refers mainly to enolates, enamines, oximes and hydrazones in which the closeness of the phosphoryl function has yielded a wealth of recent results. These are discussed separately in Sections II and IV. 

This approach was applied subsequently for the preparation of acylphosphonic acids. The bis (trimethylsilyl) esters obtained could be subjected to alcoholysis and the resulting... 

In order to gain information regarding the comparative hydrolytic stabilities of the partially or fully unesterified acylphosphonates in base, the stabilities of monomethyl acylphosphonates [RCOP(0)OMeOH] and acylphosphonic acids [RCOP(O) (OH)2] (R = Hex, Ph and MeCH=CH—) were examined as representative compounds by... 

In summary, it can be concluded that acylphosphonic acids and monoesters are far more stable than diesters in alkaline conditions. The former ionize under the influence of base, and then the phosphonyl group cannot act as a leaving group to give the C—P bond fission products. 

Acylphosphonic acids react with pyridoxamine, which is a coenzyme of transaminases, with the formation of a-aminophosphonic acids (see also reductive amination. Section II. C. 4. c) The first step of the reaction is addition of the pyridoxamine to the carbonyl of the acylphosphonate, followed by prototropic rearrangement and hydrolysis to pyridoxal and an aminophosphonic acid (equation 59). This reaction is in contrast with the reverse... 

The reaction of dialkyl acylphosphonates with sulphonic acids was reported lead to sulphonic esters and acylphosphonic acids ". Reinvestigation of this reaction using P NMR spectroscopy revealed that the reaction of equimolar amounts of dimethyl ben-zoylphosphonate and/ -toluenesulphonic acid at room temperature gives dimethyl hydro-genphosphonate (equation 71). It was proposed that the by-product of this reaction, benzoic / -toluenesulphonic anhydride, reacts with the excess / -toluenesulphonic acid to yield / -toluenesulphonic anhydride and benzoic acid. Heating these two compounds with... 

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