Esters phosphonate, reaction with

Condensations. Alumina promotes the formation of a-hydroxyphosphonate esters from aromatic aldehydes and dialkyl phosphonates, and the adducts are converted to a-aminophosphonate esters on reaction with ammonia. A solvent-free synthesis of a-nitro ketones comprises mixing nitroalkanes, aldehydes, and neutral alumina and oxidizing the adducts with wet, alumina-supported CrOj (15 examples, 68-86%). The Knoevenagel reaction, the Michael addition of nitromethane to gcm-diactivated alkenes, and the formation of iminothiazolines from thioureas and a-halo ketones are readily effected with alumina under microwave irradiation. 

Phosphonous acid diesters undergo the Arbusov reaction with a wide variety of organic halides, giving esters of secondary phosphinic acids, as is demonstrated in Eq. (88) ... 

In contrast, when excess amounts of the HHTs derived from simple aliphatic glycinate esters, such as 25, were used in excess in reactions with diaryl phosphites (SO), the related glyphosate aminals containing aryl phosphonate esters 46 were isolated in low yield (5-15%). Like many aminals, these triesters 46 were acid-sensitive and were quantitatively converted to the corresponding triester strong acid salts 47 upon treatment with either HCl or methanesulf onic acid (27). 

Trimethylsilyl esters of tris(thio)phosphonic acids 2070 are readily oxidized by DMSO in toluene at -30 °C to give the dimeric tetra(thia)diaphosphorinanes 2071 and HMDSO 7 [208] (cf. also the oxidation of silylated thiophenol via 2055 to diphenyl disulfide). The polymeric Se02 is depolymerized and activated by reaction with trimethylsilyl polyphosphate 195 to give the corresponding modified polymer... 

Olefination Reactions Involving Phosphonate Anions. An important complement to the Wittig reaction involves the reaction of phosphonate carbanions with carbonyl compounds 253 The alkylphosphonic acid esters are made by the reaction of an alkyl halide, preferably primary, with a phosphite ester. Phosphonate carbanions are generated by treating alkylphosphonate esters with a base such as sodium hydride, n-butyllithium, or sodium ethoxide. Alumina coated with KF or KOH has also found use as the base.254... 

Fluoromethyl)phosphonate ester anions react with CO2 or COS to yield esters of the type (161 Y=0 or S) which may be dealkylated to the free acid through the use of bromotrimethyl-silane, but the course of the reaction with CS2 depends on the individual ester thus, (162) yields (163), but (165) is formed from (164). 22... 

The final example of a domino process under high pressure, to be discussed in this chapter, is a combination of a Horner-Wittig-Emmons (HWE) reaction with a Michael addition developed by Reiser and coworkers [5]. Hence, reaction of a mixture of an aldehyde such as 10-18, a phosphonate 10-19 and a nucleophile 10-20 in the presence of triethylamine at 8 kbar led to 10-21. By this method, (3-amino esters, 3-thio esters and 3-thio nitriles can be prepared in high yield (Scheme 10.4). Many of these transformations do not occur under standard conditions, thereby underlining the importance of high pressure in organic chemistry. 

The insertion of the oxiranes into a P-O-C- bond of the mixed ester takes place in the reaction of the O-alkyl O-silyl phosphonates 3 with oxiranes in contrast to the reaction above. The formed 0-(2-siloxyethyl) O-alkyl phosphonates 11 show the typical PH-reactivity with the protected HO-group for further reactions. 

The 2,5-dihydro-l,2-oxaphosphole-2-oxide derivatives 196 were also obtained from the reaction of esters of 3-chloro-4-methyl-l,3-pentadiene-2-phosphonic acid with halogens (Scheme 78) [155, 156],... 

Several methods for the preparation of the parent compound in this system, tris(trimethylsilyl)phosphite, have been reported.114 118 The application of this and related reagents in reaction with alkyl halides has been reported and used for the preparation of a variety of phosphonic acid analogues of phospholipids.114119-124 Interestingly, alkyl chlorides appear to be more reactive with the silyl reagents than do alkyl iodides, a reversal of the normally observed trend with alkyl esters of the phosphorus acids. (The particular use of silyl phosphorus reagents for the synthesis of biologically significant compounds has... 

The reaction is performed most simply by the addition of the propargylic alcohol to a solution of the phosphorus halide. Rearrangement of the phosphorus ester proceeds at ambient temperature or with mild heating. When phosphorus trihalides are used, the product can be isolated as the phosphonic dichloride.168169 Aqueous workup provides the phosphonic acid.162 In most instances, however, a dialkyl phosphorochloridite with only a single halogen on phosphorus available for reaction with alcohol has been used.165 170 174... 

Lafitte, B. and Jannasch, P. 2005. Phosphonation of polysulfones yia lithiation and reaction with chlorophosphonic acid esters. Journal of Polymer Science Part A 43 273-286. 

Subsequently, List reported that although the method described above was not applicable to the reduction of a,P-unsaturated ketones, use of a chiral amine in conjunction with a chiral anion provided an efficient and effective procedure for the reduction of these challenging substrates [210]. Transfer hydrogenation of a series of cyclic and acyclic a,P-unsaturated ketones with Hantzsch ester 119 could be achieved in the presence of 5 mol% of valine tert-butyl ester phosphonate salt 155 with outstanding levels of enantiomeric control (Scheme 64). A simple mechanistic model explains the sense of asymmetric induction within these transformations aUowing for reliable prediction of the reaction outcome. It should also be noted that matched chirality in the anion and amine is necessary to achieve high levels of asymmetric induction. 

The halogen-fluorine exchange with an HF-amine complex allows the transformation of a gem-dichloro goup into a difluoro group. While this reaction is difficult to initiate in nonactivated positions, it is efficient in the benzylic position and in the a position of functional groups (e.g., esters, phosphonates) (Figure 2.10). ... 

Similar applications to those reported in CHEC-II(1996) have been described for more elaborate phosphonate esters 42 and 43 which undergo Horner-Emmons reactions with carbonyl compounds following deprotonation <2000EJ051, 2002CL1002>. 

Somewhat better results are obtained by employing a chiral phosphonate in reactions with alkyl(phenyl)ketenes, which results in destruction of the chiral phosphonate and in the enantioselective formation of allenecarboxylic esters with 15-20% optical purity114-115. 

The analogue in which carbon replaces oxygen in the enol ring should of course avoid the stability problem. The synthesis of this compound initially follows a scheme similar to that pioneered by the Corey group. Thus, acylation of the ester (7-2) with the anion from trimethyl phosphonate yields the activated phosphonate (7-3). Reaction of the yhde from that intermediate with the lactone (7-4) leads to a compound (7-5) that incorporates the lower side chain of natural prostaglandins. This is then taken on to lactone (7-6) by sequential reduction by means of zinc borohydride, removal of the biphenyl ester by saponification, and protection of the hydroxyl groups as tetrahydropyranyl ethers. 

Functionalized polymers are of interest in a variety of applications including but not limited to fire retardants, selective sorption resins, chromatography media, controlled release devices and phase transfer catalysts. This research has been conducted in an effort to functionalize a polymer with a variety of different reactive sites for use in membrane applications. These membranes are to be used for the specific separation and removal of metal ions of interest. A porous support was used to obtain membranes of a specified thickness with the desired mechanical stability. The monomer employed in this study was vinylbenzyl chloride, and it was lightly crosslinked with divinylbenzene in a photopolymerization. Specific ligands incorporated into the membrane film include dimethyl phosphonate esters, isopropyl phosphonate esters, phosphonic acid, and triethyl ammonium chloride groups. Most of the functionalization reactions were conducted with the solid membrane and liquid reactants, however, the vinylbenzyl chloride monomer was transformed to vinylbenzyl triethyl ammonium chloride prior to polymerization in some cases. The reaction conditions and analysis tools for uniformly derivatizing the crosslinked vinylbenzyl chloride / divinyl benzene films are presented in detail. 

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