Benzoylphosphonates reactions

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... 

Diethyl benzoylphosphonate, C6H5C—P(OC2H5)2 (1). Mol. wt. 242.20, b.p. 141-147°/ 3 mm. The reagent is prepared by reaction of benzoyl chloride with triethyl phosphite... 

Benzoylation of alcohols.2 This reaction with 1 is markedly catalyzed by DBU, but not DMAP. Tertiary alcohols react slowly and it is possible to effect selective benzoylation of primary alcohols in the presence of secondary alcohols. The selectivity can be enhanced by use of diisopropyl benzoylphosphonate. 

Cool the reaction mixture and replace the condenser with a fractional distillation set up. Distil the product at vacuum-pump pressure, discarding any low boiling fore-run, and collect pure diethyl benzoylphosphonate, 14 (b.p. 141°C, 2.5 mmHg, 15.7 g, 67 %), as a yellowish liquid. 

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. 

The Reformatsky reaction of ethyl bromoacetate with dunethyl benzoylphosphonate takes place readily, but the yield of the expected linal product, ethyl benzoylacetate, is low (30%).52 ... 

Griffiths, D.V., Griffiths, P.A., Whitehead, B.J., and Tebby, J.C., Novel quasiphosphonium ylides from the reaction of trialkyl phosphites with dialkyl benzoylphosphonates. Evidence for carbene intermediates in the intramolecular cyclization of 2-substituted dialkyl benzoylphosphonates. 7. Chem. Soc., Perkin Trans. 1, 479, 1992. 

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. 

Griffiths, D.V., and Karim. K.. Studies of the reactions of 2-substituted dimethyl benzoylphosphonates with trimethyl phosphite. Phosphorus. Sulfur Silicon Relat. Elem., Ill, 107, 1996. 

The reactions of trialkyl phosphites with dialkyl benzoylphosphonates have also been extensively studied. At higher temperatures, novel ylidic phospho-nates (40) are produced via phosphite trapping of intermediate carbenes. Ylidic phosphonate (40 R = PhO) had characteristic NMR signals at 831 at 53.5 and at 31.6. The phosphate (41 R = PhO), was frequently observed in the reaction products and had a very characteristic P NMR spectnim with Saip at... 

Synthesis of mixed dialkyl acylphosphonates by the Arbuzov reaction is of practical value only with mixed phosphites in which there is clear preference of the different alkyl groups to be cleaved. For example reaction of diethyl phenyl phosphite with benzoyl chloride give phenyl ethyl benzoylphosphonate (equation 6) . 

Photolysis of dimethyl a-diazobenzylphosphonate in an argon matrix doped with 20% of oxygen at 10 gave dimethyl benzoylphosphonate along with dimethyl benzoyl phosphate (equation 43) The reaction involves photochemical generation of phenyl-... 

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. ... 

Alternatively, hydroxide anion may also attack the P—O—Me group and displace benzoylphosphonate, which as a dianion is expected to be a very poor leaving group. Therefore, it is not surprising that this is the less favoured course of the reaction. 

The reaction of acylphosphonate diesters with alcohols was reported early to lead to dialkyl hydrogenphosphonates and carboxylate esters In a more recent systematic study, conditions were developed to use acylphosphonates for the acylation of alcohols. It was found that 1,5-diazabicyclo [5.4.0] undec-7-ene (dbu) is a highly effective catalyst for acylation of alcohols by acylphosphonates. Two special aspects deserve mention (1) /er butyl alcohol could be acylated with diethyl benzoylphosphonate, in the presence of dbu and 4-dimethylaminopyridine, to give r r/-butyl benzoate in 57% yield (2) the primary hydroxy group of a diol (e.g. butane 1,3-diol) could be acylated fairly selectively in the presence of a secondary hydroxy group by this methodology (ratio of mono to diacyl product =88 12). 

In contrast to dialkyl acylphosphonates, the reaction of methyl sodium benzoylphos-phonate or disodium benzoylphosphonate with methylamine gave the imine without severing the C—P bond, demonstrating that the high reactivity of the carbonyl group is preserved even in the anion (equation 58) ... 

Tetrahedral phosphorus in a five-membered ring is highly strained. To relieve this strain, such compounds tend to expand the coordination of the phosphorus to five. It was reasoned that if indeed the thermal fragmentation should proceed by the four-centred mechanism outlined above, it would proceed much more readily in a five-membered cyclic a-hydroxyiminophosphonate. To test this, a five-membered cyclic benzoylphosphonate was reacted with hydroxylamine . This reaction yielded only the (E )-oxime along with a considerable amount of benzonitrile (equation 123). This result is consistent with the... 

Stoichiometric reactions of diethyl benzoylphosphonate with a variety of amines gave amides 1 as the main products along with diethyl H-phosphonate 2 and a-(phosphoryl-oxy)benzyl phosphonates 3 [235]. The use of hindered diethyl benzoylphosphonate resulted in high yield of amides in the case of primary amines and poorer yields of amides in the case of the reaction with a hindered amine such as diethylamine. 

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