Alkenylphosphonate esters

The epoxidation of halogenated alkenylphosphonic esters with trifluoroperoxyacetic acid yields unstable halogenated (epoxyalkyl)phosphonic esters, which isomerize rapidly by a 1,2-shift of halogen. The isomerization occurs for both 1,2-epoxyalkyl and 2,3-epoxy alkyl compounds, but in some cases the rearrangement is not regiospecific and affords both ketonic and aldehydic products ... 

Good results are obtained from react Thus, 1,3-asymmetric induction in the addi > the isopropyl group of the dilactim ( -onjugated sulfones, and 1,5-asymmetrK ire addition to alkenylphosphonate esters-... 

Other interesting electron-deficient olefin substrates for the asymmetric conjugate addition include cr-acet-amidoacrylic ester SI,101 dimethyl itaconate S2,114 ct,/3-unsaturated sulfones S3,115 and alkenylphosphonate S4116 (Figure 8). 

Petrov, K.A., Raksha, M.A., Korotkova, V.P., and Shmidfi E., Synthesis and properties of alkenylphosphonic derivatives. Part 4. P-Aldo phosphonic esters, Zh. Obshch. Khim., 41, 324, 1971 7. Gen. Chem. USSR (Engl. Transl.), 41, 319, 1971. 

Ohler, E., and Kotzinger, S., Thermal reanangement of trichloroacetimidic esters of allylic a-hydroxyphosphonates. A convenient way to (3-amino-1-alkenylphosphonic acids, Synthesis, 497, 1993. 

Pyrolysis (in boiling toluene) of the sulphoxide obtained from a dialkyl (l-phenylth> ioalkyl)phosphonate (339) and 3-chloroperoxybenzoic acid affords an alkenephosphonic diester, and subsequent work showed that the sequence was adaptable to the production of chiral esters of alkenylphosphonic diester with optical purities of not less than 93%. Use of the ( S )p-phosphonic amide 340 afforded a mixture of the (E)-(S)p- and (Z)-(S)p-stereoisomers (341), separable by chromatographic methods. ... 

The use of esters of a (substituted-methyl)phosphonic acid to provide the carbanion site next to phosphoryl phosphorus was a natural step forward. The most successful development has been the use of the carbanion 346 derived from esters of methylenebisphospho-nic acid (or its monoalkylated derivatives). The anion 346 reacts with an aldehyde to afford the alkenylphosphonic diester 347 (R = Et, Ph, PhCH—CH, 2-thienyl, 2-pyridinyl, etc,) ". Use of the protected 3-pyridinylcarboxaldehyde 348 allowed the preparation of the ester 349, which, after reduction of the C=C bond and hydrolysis, afforded the phosphonic acid 350 Such reactions have also been carried out under phase-transfer condi-tions. Reactions between the lithium salt of the ester 351 and benzaldehyde or but-2-enal give the (alk-1 -enyl)phosphonic esters 352 and 353 in the ratio 1 4 the lithium salts 354 and 355 are formed concomitantly in the ratio 4 1. ... 

Esters and other derivatives of alkenyl- and alkynyl-phosphonic acids, and of the correspondingly unsaturated phosphinic acids, undergo a wide range of addition and cycloaddition reactions which will be considered more fully in Chapter 6. These reactions include applications of the Diels-Alder reaction to yield carbocyclic phosphonic acids based on mono- and poly-cyclic ring systems, some of which are precursors to other aromatic phosphonic acids. A typical example of this procedure is the addition of dimethyl (bromoethynyl)phosphonate to 2,3-dimethylbutadiene elimination of HBr from the 1 1 cycloadduct, using Et3N, affords dimethyl (2,3-dimethylphenyl)phosphonate. The addition of carbenes to alkenylphosphonic derivatives yields those of cyclopropylphos-phonic acids. ... 

The addition of a nitroalkane to an alkenylphosphonic diester is exemplified by the interaction of nitromethane with diethyl ethenylphosphonate in the presence of NaOEt, when the product is diethyl (3-nitropropyl)phosphonate and by a similar addition to 1,1-bis(diethoxyphosphinoyl)ethane . In the initial stages of a synthesis of (4,5,6-trihydroxy-3-oxohexyl)phosphonic acid, the nitro sugar 76 was made to add to dibenzyl ethenylphosphonate, but the resultant (3-nitropropyl)phosphonic dibenzyl ester 77 was then used without isolation. ... 

An unexpected alkenylphosphonate product has arisen in an HWE reaction, but it can be suppressed by bulking up the aldehyde or ester reactant. ... 

Hayashi has reported a wide range of reactions employing rhodium with chiral binaphthylphosphine ligands, for example in the asymmetric 1,4-addition of boronic acids and triarylboranes to various unsaturated starting materials a,p-unsaturated ketones, esters, 1-alkenylphosphonates, nitroalkenes and 5,6-dihydro-2(lH)-pyridinones. ... 

In the cases of a-silylalkylphosphonates 98 bearing a hydro, fluoro, chloro or al-koxy group on the silyl-bearing a-carbon atom, the reactions of the corresponding carbanions with aldehydes give mixtures of the E- and Z-isomers of the alkenylphosphonates 99 (Scheme 2.59) [160-165]. Olefination reactions can also be achieved by using phosphonates, such as 100, with ketones or, in some cases, esters as substrates (Scheme 2.60) [42, 166]. 

Reactions with aldehydes of carbanions bearing three different atoms on the anionic carbon atom prepared from a-silyl-a-sulfanylalkylphosphonate 101 give the corresponding ( )-l-alkenylphosphonates 102 with high selectivities (Scheme 2.61) [167]. Such high -selectivity is also seen in the Peterson reactions of a few fluo-romethylphosphonates such as 103 with trifluoroacetate esters (Scheme 2.62). 

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