Arylphosphonic acids, synthesis

The Bart reaction has now been extended to the synthesis of arylphosphonic acids by the interaction of the diazonium fluoroborate and phosphorus trichloride (Doak and Freedman, 1951). 

Other methods for synthesis of arylphosphonic acids or their derivatives fall into four main categories. First, many aromatic compounds react with PC13 under catalysis by A1C13 to form aryldichlorophosphines (ArPCl2).9a n These add chlorine to form... 

A one-pot procedure for the synthesis of arylphosphonic acid monoalkyl esters (the hexyl esters were chosen in practice) started... 

The chlorophosphonium complexes 39, produced (Scheme 8) during the synthesis of cyclic esters of arylphosphonic acids from aryldiazonium tetrafluoroborates and cyclic chlorophosphites, are decomposed by H2S to give the analogous esters of arylthiophos-phonic acids ... 

In the same year, a rhodium(III)-catalyzed cyclization by employing alkenes and arylphosphonic acid monoesters for the synthesis of benzoxaphosphole 1-oxides was reported by Lee and coworkers (Scheme 6.9) [17]. Using the combination of... 

Scheme 6.9 Synthesis of benzoxaphosphole 1-oxides from arylphosphonic acid monoethyl esters and alkenes.

Scheme 6.25 (a) Synthesis of phosphaisocoumarins from phenylphosphinic acids and (b) synthesis of phosphaisocoumarins from arylphosphonic acid monoesters. 

Reports on arylphosphonates include the synthesis and resolution of new racemic phosphonic acid methyl (213) and dimethyl esters (214) via cinchonium salts (Scheme 56). The absolute configuration of the phosphonic ester products was also established. 

Obrycki. R.. and Griffin. C.E.. Phosphonic acids esters. Part 19. Syntheses of substimted phenyl- and arylphosphonates by the photoinitiated arylation of trialkyl phosphites, J. Org. Chem., 33, 632, 1968. Engel. R.. Synthesis of Carbon-Phosphorus Bonds, CRC Press, Boca Raton, 1988, p. 137. 

The mode of reaction of alkyl- or arylphosphonic halides with Grignard reagents in ether is most often unpredictable. Bis(p-tolyl)phenyl-phosphine oxide is reported as the major product from phenylphos-phonic dichloride and the required quantity of Grignard reagent (148). Attempted synthesis of diallylphenylphosphine oxide under similar circumstances gave only undistillable black oils and tars (13). Equimolar quantities of reactants furnished diphenylphosphinic acid in good yield plus a small quantity of triphenylphosphine oxide (45). 

SCHEME 4.258 Copper-catalyzed synthesis of arylphosphonates using arylhoronic acids in air [411],... 

The copper-catalyzed coupling of boronic acids with hydrogen phosphonates is an attractive approach to the synthesis of arylphosphonates because the reaction can be carried out under an atmosphere of air at room temperature (Scheme 4.258) [411], A wide variety of preexisting functional groups were well tolerated by this approach, and the isolated yields were excellent. The reaction time was a bit long (24h) however, the ability to eliminate the use of a glovebox or even a vacuum line makes the reaction very practical. 

Johansson T, Stawinski J. Studies towards synthesis of dinucleoside arylphosphonates with metal complexing properties. Nucleos. Nucleot. Nucleic Acids 2003 22 1459-1461. 

Roschenthaler and co-workers have reported a new methodology for the synthesis of ort/ o-CF2X-substituted arylphosphonates (750) via the Diels-Alder reaction of selected 1,3-butadienes (749). The reactivity of (750) was then examined to give the respective phosphine oxides (751), carboxylic acid (754), -ethens of type ArCF = CFAr (752) and nucleophilic substitution reaction products (753) with various electrophiles (Scheme 191). " " ... 

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