Benzoylphosphonic acids

Benzoic acid (271) when reacted with PCI3 yielded an adduct (272) which underwent an Arbuzov rearrangement to the phosphoryl compound (273), which eliminated 3HC1 to give benzoylphosphonic anhydride (274). Addition of water to the reaction mixture converted the anhydride (274) into benzoylphosphonic acid (275), which underwent... 

The intermediacy of benzoylphosphonic acid was postulated in the reaction of benzoyl chloride with phosphorous acid, which gave a-hydroxybenzylidenebisphosphonic acid as one of the final products. ... 

Another interesting case is that of 6 -hydroxybenzoylphosphonic acid (24), which was reported to hydrolyse to the extent of 15% at 100 °C, pH 8.8 In contrast, no decomposition was observed when benzoylphosphonic acid was kept under the same conditions. It appears reasonable to asssume that the excessive stability of the nucleoside derivative 23 is the result of steric hindrance due to the large nucleoside bound to the phosphoryl group. On the other hand, the increased reactivity of o-hydroxybenzoylphosphonic acid (24) compared with the unsubstituted compound indicates that the c -hydroxy group probably participates intramolecularly in the fission of the C—P bond. 

In the presence of [PdMe2(PMePh2)3] diethyl benzoylphosphonate is degraded during minutes and with quantitative yield, into diethyl phenylphosphonate (l-oxoalkyl)phosphonic esters suffer a similar fate but the process may take several hours under the same conditions. When mixtures of aroylphosphonic diesters and esters of (l-oxoalkyl)phosphonic acids are brought into contact with the... 

A new method of cyclization has been developed, through the reaction of suitably or//ru-substituted diethyl benzoylphosphonates (41), or their acid chloride precursors, with trialkyl phosphites. An analogous reaction takes place with (42) to give the fluorenylphosphonate (43). The mechanism suggested involves initial attack on carbonyl oxygen, and gains support from the formation of the benzofuranylphosphon-ate (45) in the reaction of (44) with triethyl phosphite. 

Pudovik, A.N., Gur yanova, I.V.. and Zimin. M.G.. Reaction of the monoethyl ester of ethylthiono-phosphinic acid with some substituted benzoylphosphonates, Zh. Obshch. Khim., 38, 1533, 1968 J. Gen. Chem. USSR (Engl. Transl.). 38. 1483. 1968. 

Results concerning the behaviour of two unique acylphosphonate derivatives under hydrolytic conditions should also be mentioned. The aroylphosphonic group was used as a protecting group in the synthesis of nucleotides. In the course of this work, the stability of this group was determined examining a series of 5 -(dimethoxytrityl) thymidine-3 -aroylphosphonates (23) in 1 M sodium hydroxide-pyridine (1 1, v/v) . These aroylphosphonate monoesters were resistant to hydrolysis. In comparison, methyl sodium benzoylphosphonate under these conditions underwent complete hydrolysis to benzoic acid in 18 hat 25 °C ... 

Reduction of the benzoylphosphonate anion and its monomethyl ester by sodium borohydride gave the corresponding a-hydroxyphosphonates Reduction of an a,j5-unsat-urated acylphosphonate by sodium borohydride under carefully controlled conditions (0-5 °C, pH 6-7) was one of the possible synthetic routes to the corresponding a-hydroxy a,y-unsaturated phosphonates, which served as starting materials towards 3-aminoalk-l-enylphosphonic acids (equation 77). ... 

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