Dimethyl- phosphonate

Thiophenol, TEA, DMF or dioxane." In the case of dimethyl phosphonates, this method can be used to remove selectively only one methyl group. Lithium thiophenoxide is also effective. ... 

Phenylimino)methyl]quinoxalme (186) with dimethyl phosphonate gave 2-[a-amlmo-a-(dimethoxyphosphinyl)methyl]quinoxalme (187) (MeONa, MeOH, reflux, several hours >95%) or with diphenylphosphine oxide gave 2-[a-anilino-a-(diphenylphosphinyl)methyl)quinoxaline (188) (MeONa, EtOH, 0°C, 20 min 95%) several analogs likewise. 

The peroxide-catalysed addition of dimethyl phosphonate to norborna-diene gives nortricyclenes as well as norbornenes. Usually, radicals react with this diene to give only nortricyclene derivatives. The ease of hydrogen abstraction from the parent phosphonate undoubtedly favours trapping of radical (8). 

C-P lyase has a broad snbstrate specificity and, for example, dimethyl phosphonate is degraded to methane, methylphenyl phosphonate to benzene, and the degradation of the widely nsed herbicide glyphosate may follow alternative pathways both of which involve C-P fission. 

Me(Ph)SiCl2 reacts with dimethyl phosphonate in a 1 1-mixture at 100°C to the O.O-disilylated phosphonate. In contrast to this observation the O-alkyl O-silyl phosphonate is formed solely by reaction of both compounds in acetonitrile at 80°C (line 7,8). An excess of the corresponding phosphonate as polar solvent leads to the mixed ester 2 only. The excess of the dialkyl phosphonate is removed from the mixture by vacuum distillation (line 9). 

Tetraphenylcyclopent-3-enone and dimethyl phosphonate are the major products from the base-catalysed reaction of methyl phosphonate with tetra-cyclone.75 A mechanism involving initial hydride transfer from dimethyl phosphinate anion to the ketone followed by kinetically controlled protonation to give (98) is suggested. 

The effect of the leaving group was briefly examined, but cinnamyl bromide gave a substantially lower ee (38%). Cinnamyl dimethyl phosphonate, or acetate, gave very poor results. The cyclohexyl-substituted allylic acetate 21, on the other hand, afforded a completely y-selective reaction, but the product turned out to be racemic. Changing the Grignard reagent halide from bromide to either chloride or iodide resulted in very low ees. 

Quantitative NMR examination of the hydrolysis of dimethyl phosphonate (245) using 0-enriched water under base-catalysed conditions supports a mechanism involving P—O rather than C—O bond cleavage. 

The H-P bond in hydrogen phosphonates readily adds across a C=C bond [22]. Upon treatment of 1-octyne with dimethyl phosphonate in the presence of a palladium complex in refluxing tetrahydrofuran, the addition reaction proceeds smoothly to afford dimethyl l-octen-2-ylphosphonate (2) regio-and stereo-selectively (Scheme 18). 

Rhodium complexes are not active in the addition reaction of acyclic hydrogen phosphonates such as dimethyl phosphonate. However, RhCl(PPh3)3 has proved to catalyze the reaction efficiently when the five-membered one 4a was used [24]. 

Chem. Abstr. Serv. Reg. No.. 868-85-9 Chem. Abstr. Name. Dimethyl phosphonate... 

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. 

Isotope effects are small, (kH/kD)max at 25° is only 3.6 and values varying from 2.2 to 3.1 were found33). The correlation with bond energy only showed up in the contrast between the aliphatic and benzyl radicals. Another study34) was the addition of dimethyl phosphonate and dimethyl thionephosphonate to olefins, in which the transfer step is reaction (11). Here variation of R with both X=0 and... 

SYNS BIS(HYDROXYMETHYL)PHOSPHINE OXIDE DIMETHOXYPHOSPHINE OXIDE DIMETHYL ACID PHOSPHITE DIMETHYLESTER KYSEUNY FOSFORITE (CZECH) DIMETHYLFOSFIT DIMETHYLFOSFONAT DLMETHYLHYDRO-GENPHOSPHITE DLMETHYL PHOSPHITE DIMETHYL PHOSPHONATE DIMETHYL PHOSPHOROUS ACID HYDROGEN DIMETHYL PHOSPHITE METHYL PHOSPHONATE NCI-C54773 PHOSPHOROUS ACID DIMETHYL ESTER... 

Thus, for example, the reaction of l,6-anhydro-2-oxo-carbohydrate 192 with dimethyl phosphonate gives rise to the 2-phosphonate derivative 193 with a high stereoselectivity (O Scheme 82) [128]. And the addition of dimethyl phosphonate to the ulose 194 in the presence of DBU affords the (5R)-5-(dimethylphosphinyl)-D-lyso-hexofuranoside derivative 195a and its (55)-epimer 195b (O Scheme 82) [129]. 

Tosylhydrazones can also undergo additions of pentavalent phosphorus derivatives, such as alkyl phenylphosphinate [Ph(H)P(0)OR] dimethyl phosphonate [HP(0)(OMe)2], or dimethyl phenylphosphonate [PhP(0)(0Me)2], to introduce phosphorus atoms. 

As noted in the discussion of ( )-selective alkene formation, Kishi has found that a-substituted aldehydes reacted with trimethylphosphonopropionate and KOBu to produce the (Z)-alkene selectively. A strongly dissociating base is critical to this approach. In addition to the examples already presented in the discussion of ( )-alkene formation, the (Z)-selective reaction has recently been applied to the synthesis of macrolide antibiotics. In this example, a trisubstituted alkene was formed and closed to the lactone (148 equation 33). In an application to diterpenoids. Piers encountered an example of how substrate-specific the alkene formation can be. With a-dimethoxyphosphonyl-y-butyrolactone (150), the reactions with simple aldehydes proceeded with very high selectivity [(Z) ( ) = 99 1]. On application of the reaction to the more complex aldehyde (149) the (Z) ( ) stereoselectivity dropped to 3 1 in 58% yield (equation 34). No selectivity was observed on reaction with benzaldehyde. Although for hindered substrates, strongly basic conditions with a dimethyl phosphonate can be a simple and effective method for the synthesis of (Z)-isomers, the reaction is not general. In 1983, Still and coworkers introduced methodology that used bis(trifluoroethyl)phosphonoesters (153) to provide a facile approach to (Z)-aIkenes (154) when reacted with aldehydes (equation 35). " ... 

Attack on Nitrogen. The kinetics of the reaction of diazonium salts with dimethyl phosphonate have been studied. The almost third-order behaviour supports the mechanism shown, involving a phosphonate anion rather than a... 

Dimethyl O-p-Nitrophenyl Thiophosphate 0,0-Dimethyl-0,p-(dimethylsulfamoyl)phenyl Phosphorothloate 0,0-Dimethyl Phosphonate 0,0-Dimethyl-S-(benzaziminomethyl)... 

The phosphorus analogs of enamide esters, the dimethyl phosphonates can be reduced by Knowles catalyst to provide the corresponding a-amido phosphonates (Fig. 8) [25]. 

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