Of dialkyl phosphites

Base-catalysed addition of dialkyl phosphites to activated olefins such as, / -unsaturated ketones and carboxylic acid derivatives25-27 is appreciably easier, the reaction being exothermic and often giving high yields. Here too it is essential that there be no more than slight steric hindrance around the double bond because otherwise the phosphite may add to the carbonyl double 

Dibutyl 2-cyanoethylphosphonate 27 A saturated solution of sodium butoxidein 1-butanol is added dropwise to a stirred and cooled mixture of dibutyl phosphite (97 g) and acrylonitrile (26.5 g) until the temperature ceases to rise. The mixture is then heated under reflux on a water-bath for a further 30 min, after which distillation affords the phosphonate (106 g, 80%), b.p. 143-144°/0.8 mm, nD23 1.4420. 

Unlike radical addition of dialkyl phosphites to vinyl esters, which occurs at the /9-position,2 8,2 9 the base-catalysed addition takes place at the a-posi-tion 29 

Enamines add dialkyl phosphites with unusual ease no catalyst is needed and addition is at the -position.30 

Like dialkyl phosphites, dialkyl phosphinites R2PHO can be added under basic catalysis to, jS-unsaturated nitriles, esters, and amides.31 

---

Diesters of phosphorous acid are in general neutral because the phosphorous acid exists mostly in the phosphonate form with one hydrogen directly attached to the phosphorus. But with alkali metals the H can be changed against the alkali and reactive intermediates formed. Such alkali metal derivatives of dialkyl phosphites react with alkyl halides to give dialkyl alkanephosphonates, according to Eqs. (45) and (46). 

In the presence of strong alkali dialkyl phosphites can be added to unsaturated compounds. Thus salts of carboxyethyl- or dicarboxyethylphosphonic acid are obtained by addition of dialkyl phosphites to methyl acrylate [99] in the presence of sodium methylate in methanol. Diethylmaleate similarly gave diethyldiethylphosphonosuccinate [100], according to Eqs. (55) and (56) ... 

The 9,10-phosphonostearic acid in form of its sodium salt shows a good thermal stability and was efficient as an inhibitor in rust protection. The diethyl-phosphonoacetoxystearic acid methyl ester is used as additive in high-pressure lubricants. Rust protection properties are also shown by 9,10-phosphonostearyl alcohol [157]. Trisodium 9,10-phosphonostearate possesses the best surface activity in an 0.2% aqueous solution showing 33 mN/m at 30°C and a pH value of 10.5 [156]. By the addition of dialkyl phosphite to a,p-unsaturated ketones the y-oxophosphonic acids are available [159]. Addition of dialkyl phosphite to y-ketoacids leads to a-hydroxy-y-carboxyphosphonates see Eq. (86) ... 

A -Acyl salts of nitrogen heterocycles phosphorylate in the hetero-ring, rather than at the carbonyl group, to give, for example, (25). The addition of dialkyl phosphites to ynamines has been reported. The products... 

Pyridylphosphonic acid derivatives (68) have been prepared by addition of dialkyl phosphite anion to A-alkoxypyridinium salts. Similar compounds, it is reported, are formed from trialkyl phosphites with... 

Han and Tanaka reported that Pd(0) complexes catalyze the addition of dialkyl phosphites to terminal alkynes to give alkenylphosphonates (Scheme 5-17, hydrophosphorylation) [15]. 

Metal-catalyzed asymmetric addition of dialkyl phosphites to aldehydes (Pudovik reaction) has been extensively developed since the initial reports in 1993 by Shibuya. Scheme 5-25 illustrates the use of TiCh to promote diastereoselective addition of diethyl phosphite to an a-amino aldehyde. 

Shibasaki showed that an aluminum-lithium-BINOL complex (ALB) also catalyzes the asymmetric addition of dialkyl phosphites to aldehydes, with ees ranging from 55 to 90% for aryl or unsaturated aldehydes (Scheme 5-37). 

The base-catalyzed reaction of dialkyl phosphite with nitroalkenes results in the formation of alkenyl phosphonates (Eq. 4.33).39... 

Pudovik, A.N. and Arbuzov, B.A., Addition of dialkyl phosphites to unsaturated compounds. I. Addition of dialkyl phosphites to 2,2-dimethyl vinyl ketone, Zh. Obshch. Khim. S.S.S.R., 21, 382, 1951. 

A Michaelis-Becker approach using the sodium salt of dialkyl phosphites has been successful for the formation of C-P bonds to aromatic rings.184 Reaction of the dialkyl phosphite in DMF with the appropriate diaryliodonium halide provides the corresponding dialkyl arylphosphonate in good yield (81 to 93%). This approach to the arylphosphonate esters proceeds in superior yield under relatively mild conditions and therefore is one to be accorded serious consideration for the preparation of such materials. 

An intriguing reaction of salts of dialkyl phosphites with the methylenetriphenylphosphoranylideneamino derivative of benzo-... 

Anionic phosphorus has been used as well in a number of recent reports of additions to carbonyl compounds. Addition of dialkyl phosphite to aromatic aldehydes in the presence of catalytic amounts of La-BINOL and dilithium (R)-binaphthoxide occurs enantioselec-... 

Several reports have been made of the addition of dialkyl phosphites and related monobasic trivalent phosphorus species to alkenes in the presence of an organic peroxide and acetic acid (Equation 3.28).439-441... 

The generation of aromatic C-P linkages can be accomplished by the reaction of dialkyl phosphites with quinones in the presence of catalytic amounts of acetic acid.449 Excellent yield of the mono-phosphorus product is reported using benzene as the solvent. 

Atherton, F.R., Openshaw, H.T., and Todd, A.R., Phosphorylation. II. Reaction of dialkyl phosphites with polyhalogen compounds in the presence of bases — method for the phosphorylation of amines, /. Chem. Soc., 660, 1945. 

Steinberg, G.M., Reactions of dialkyl phosphites — synthesis of dialkyl chlo-rophosphates, tetraalkyl pyrophosphates, and mixed orthophosphate esters, /. Org. Chem., 15, 673, 1950. 

Sidky, M.M., Mahran, M.R., and Zayed, M.F., Organophosphorus compounds. XXIX. On the reaction of dialkyl phosphites with p-ben z.oqu i noned i benzene-sulfonamide, Phosph. Sulf, 9, 337, 1981. 

Tewari, R.S. and Shukla, R., Reactions of dialkyl phosphites with a,fi-unsat-urated ketones, Ind.. Chem., 10, 823, 1972. 

Sidky, M.M., Soliman, F.M., and Shabana, R., Organophosphorus compounds. XIV. Reaction of dialkyl phosphites and thiol acids with 4-benzylidene-l,2-diphenyl-3,5-pyrazolidinedione, Egypt. J. Chem., 15, 79, 1972. 

Smith, T.D., Reaction of dialkyl phosphites with cupric chloride, /. Chem. Soc., 1122, 1962. 

Figure 6.20 Addition of dialkyl phosphites across acetylenic linkages.

Corresponding replacement of halide from an unconjugated vinylic site has also been reported. The use of the sodium salts of dialkyl phosphites in tetrahydrofuran at low temperature has been found to provide the vinylic phosphonate in good yield,72 (Figure 6.22) and triisopropyl phosphite serves similarly to replace a fluoride of trifluoroiodoethene (Figure 6.23).91 The reaction proceeds ste-reospecifically to replace the fluoride cis to the iodide, and in continuing reaction the iodide is replaced. 

Figure 6.21 Addition-elimination of dialkyl phosphite salts with a,P-unsaturated carbonyl compounds.

Boulos, L.S. and Arsanious, M.H.N., The novel behavior of dialkyl phosphites toward 1,4-benzoquinone monoimines, Tetrahedron, 49, 4711, 1993. 

Pudovik AN (1952) Addition of dialkyl phosphites to imines. New method of synthesis of esters of amino phosphonic acids. Dokl Akad Nauk SSSR 83 865-868... 

Simoni, D., Rondanin, R., Morini, M., Baruchello, R. and Invidiata, F.P., 1,5,7-triazabicyclo 4.4.0 dec-l-ene (TBD), 7-methyl-TBD (MTBD) and the polymer-supported TBD (P-TBD) three efficient catalysts for the nitroaldol (Henry) reaction and for the addition of dialkyl phosphites to unsaturated systems, Tetrahedron Lett., 2000, 41, 1607. 

Table 4 Yields of Dialkyl Arylphosphonates Formed in the Photostimulated Reaction of Dialkyl Phosphite Ions with Aryl Halides ArX + (ROhPO" - (RO>2P( —Q)Ar ...

The use of diaryliodonium salts for direct arylations of nucleophilic species is a well-established practice. Examples of C-heteroatom bond formation by this approach, including uncatalyzed arylations of dialkyl phosphite, thiocarboxy-late, arylthiosulfonate, dialkyl phosphorothiolate, arylselenolate, and aryltel-lurolate salts with symmetrical diaryliodonium halides, are shown in (Scheme 40) [110-115]. 

The introduction of a phosphorus-containing group into the side chain of the hydrazone fragment of isatin was reported in [97]. The results of a study of the kinetic relationships and mechanism of the addition of dialkyl phosphites to substituted benzylideneamines, which were related to the basicity of the initial amines, were published as abstracts in [98]. 

The addition of dialkyl phosphites at the C=C bond of l,3,3-trimethyl-2-methyleneindoline, leading to l,2,3,3-tetramethyl-2-phosphorylindolines 181 was described in [31, 193] ... 

For reviews of the Michaelis-Becker reaction, see Refs 6,13,14, and 59 the latter is one of a series of five reviews by Troev on the structure and reactions of dialkyl phosphites.59-63... 

---