Diethyl arylphosphonates

Diethyl arylphosphonates were synthesized by reactions of diethyl phosphonate with aryl iodides or bromides containing electron-donor or electron-acceptor substituents in the aromatic ring in aqueous MeCN or neat H2O in the presence of Pd complexes with water-soluble ligands.34 For example, MeCN/H20 (1 mL), PhBr (8.2 mmol), and Ph2P(C6H4S03Na-m) (approximately 0.4 mmol) were successively... 

Petrakis, K.S., and Nagabhushan, T.L., Palladium-catalyzed substitutions of triflates derived from tyrosine-containing peptides and simpler hydroxyarenes forming 4-(diethoxyphosphinyl)phenylala-nines and diethyl arylphosphonates, J. Am. Chem. Soc., 109, 2831, 1987. 

Reactions between diethyl hydrogenphosphonate and ArX (X = I or Br) to give diethyl arylphosphonates have been carried out in the presence of a phase transfer catalyst. Bis(trimethylsilyl) phenylphosphonite reacts with alkyl halides to give [(ar)alkylphenyl]phosphinic derivatives, and it also adds to a,P-unsaturated carboxylic esters (as well as to nitriles and amides) to give (2-functionalized-l-alkyl)phosphinic derivatives. ... 

Arylphosphonic acids. Diethyl arylphosphonates can be prepared by reaction of aryl iodides (bromides react more slowly) with this reagent in the presence of sodium in liquid ammonia with irradiation of about 300-350 nm. This arylation is believed to involve radical and radical anion intermediates (SrnI mechanism). ... 

An effcient Pd-catalyzed, carbon-phosphorus bond-forming route has been described for the direct synthesis of diethyl arylphosphonates (451) bearing amino and alkylamino groups on the aromatic ring from bro-moanilines (450) (Scheme 112). ... 

The synthesis of ort/zo-difluoromethylaryl-dimethylphosphine oxide was elaborated by Roschenthaler et al. utilizing a Claisen-type condensation, dehydration, cycloaddition and aromatization. Diethyl arylphosphonates were obtained as intermediates. The change in the P-functionality led to the desired aryl-dimethylphosphine oxides (Scheme 54). ... 

Potassium dialkyl phosphite ions react rapidly with aryl iodides in liquid ammonia under irradiation to form diethyl esters of arylphosphonic acid in almost quantitative yields238. The photostimulated reaction of (EtO)2PO ions with 5-chloro-7-iodo-8-isopropoxyquinoline gave 70% of the substitution product with retention of the 5-chloro substituent239. The same nucleophile was formed in THF, and in a mixture of solvents (1 4 THF MeCN) reacts under irradiation with ArX (o-, ra-,/ -iodoanilines, 2-iodo, 3-iodo, 2-bromo and 3-bromopyridines and 3-bromoquinoline) rendering the substitution product in high yields (70-98%) (equation 130)240. 

Diethyl l-(ethoxycarbonyl)methylphosphonate can be selectively C-alkylated in comparable yield (65%) using the less expensive (chloromethyl)trimethylsilane in heterogeneous conditions with dry KgCOg at 60"C in the presence of a small amount of Nal. The rzz7//rz-(trimethylsilyl)arylphosphonates... 

Dialkyl arylphosphonates are also obtained from sodium dialkyl phosphites and aryl halides in the presence of Cu I in HMPTin a similar reaction, diethyl (l-cycloalkenyl)phosphonates with carbon rings having up to 12 atoms were prepared in 50—70% yields from the 1-cycloalkenyl chloride and the copper(i) adduct from triethyl phosphite. ... 

The addition of secondary phosphites to arynes is an attractive procedure for the formation of arylphosphonates (Schemes 4.211 and 4.212) [332]. The resulting arylphosphonates were formed in moderate to excellent yields, and a range of substrates were compatible with the reaction chemistry with the provision that they possessed a TMS group adjacent to a triflate. In addition to the tertiary phosphites, diethyl phenylphosphonite was successfully added to the arynes to generate arylphosphinates. This approach is a potentially valuable way to generate arylphosphonates or phosphinates under mild conditions without the addition of transition metals. 

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