Dimethyl methylphosphonate, preparation

The dimethyl methylphosphonate (XI) can also be readily prepared by the Arbusov rearrangement of trimethyl phosphite 3... 

Prepared by bulk polymerization, an MIP for the detection of dicrotophos based on the Eu3+ complex has recently been presented [58]. The authors used reversible addition fragmentation chain transfer (RAFT) polymerization followed by ring closing methathesis (RCM) to obtain the star MIP with arms made out of block copolymer. The star MIP containing Eu3+ exhibited strong fluorescence when excited at 338 nm with a very narrow emission peak (half width -10 nm) at 614 nm. This MIP was sensitive to dicrotophos in the range of 0-200 ppb, but showed saturation above this limit. Cross-reactivity of this MIP was evaluated with respect to structurally similar compounds dichlorvos, diazinon and dimethyl methylphosphonate. In these tests no optical response of the polymer was detected even at concentrations much higher than the initial concentration of dicrotophos (>1000 ppb). 

Preparation of the DHAP analogue, 4-hydroxy-3-oxobutylphosphonic acid, which is an effective donor substrate, is accomplished in four steps from glycidol.29 Glycidol is silyl protected then its epoxide is opened by dimethyl methylphosphonate. The secondary alcohol was oxidized under the Dess-Martin conditions. Deprotection of the alcohol followed by phosphate hydrolysis, generated the DHAP phosphonate analogue (Scheme 5.9). 

Phosphonate esters can be prepared either by the Arbuzov reaction (rearrangement) or by the alkylation of esters with DMMP (dimethyl methylphosphonate) (Scheme 4.28). Variation of the reaction conditions and reagents allows one to synthesize E- and Z-aUcenes with a high degree of stereoselectivity, as shown in Scheme 4.29. For example, 6-heptenal (4.33) on reaction with 4.34 in the presence of NaH gives -nonadienoate (4.35) on the other hand, in the presence of a base n-BuLi, Z-nonadienoate (4.36) is the major product. 

Chiral vinyl sulfoxides can also be prepared Horner-Emmons reaction of carbonyl compounds with a-phosphoryl sulfoxides which are obtained from lithiated dimethyl methylphosphonate and (-)-menthyl (S)-p-toluenesulfinate (eq 8). However, this reaction applied to carbonyl compounds often gives a mixture of the (E) and (Z) isomers of the vinylic sulfoxide. 

G.A. Kraus and co-workers utilized the quasi-Favorskii rearrangement of a bicyclic bridgehead bromide as the key step in their formal total synthesis of ep/-modhephene. The required bicyclo[3.3.1]nonenone bridgehead bromide precursor was prepared by a Robinson annulation reaction between 3-bromo-2-oxocyclohexanecarboxylate and MVK. Upon treatment with lithiated dimethyl methylphosphonate, the bicyclic bromo ketone underwent a facile quasi-Favorskii rearrangement to afford the key intermediate bicyclo[3.3.0]octane derivative. 

The preparation of methyl (carbomethoxymethyl) methyl phosphonate was conducted with methyl chloroacetate and an excess of dimethyl methylphosphonate, using sodium carbonate as a catalyst (27). 

A relatively general procedure for the preparation of dialkyl 2-oxoalkylphosphonates by direct acylation of dialkyl 1-lithioalkylphosphonates has been introduced by Corey and Kwiatkowski in 1966. The use of phosphonate carbanions as nucleophiles in reaction with carboxylic esters avoids the problems associated with the Michaelis-Arbuzov reaction. The reaction sequence is initiated by the addition at low temperature of dimethyl 1-lithiomethylphosphonate (2 eq and frequently more) to a carboxylic ester (1 eq) to give the transient lithium phosphonoenolate. The dimethyl methylphosphonate, being readily available and easy to eliminate, is the most frequently used phosphonate, but other phosphonates such as diethyl and diisopropyl methylphosphonates can be used. When the resulting enolate is treated with acid, dimethyl 2-oxoalkylphosphonate is produced in moderate to good yields (45-95%, Scheme 7.20). The reaction has been achieved with... 

Tzou and Weller (1994) have studied the catalytic oxidation of dimethyl methylphosphonate (DMMP), a nerve gas stimulant, over laboratory-prepared Pt/AbOs as a function of Pt loading (0.5 or 2.0%) and temperature (150, 250, or 400 °C).A conventional flow system was used for the activity studies. They identified intermediate phosphorous-containing compounds in the reactor effluent after catalyst activity decline and looked for evidence of aluminum phosphate in the catalyst, which could be produced by reaction of alumina support with phosphoric acid. 

For the preparation of prostacyclin derivative ([3- " C]nonyl)SM-10902 1821. halo-decarboxylation of (35)-3-methylheptanoic acid 1781 gave key intermediate 79. Grignard reagent preparation, carboxylation with " COj, esterification and subsequent reaction of the resulting ethyl ester with lithiated dimethyl methylphosphonate afforded ketophos-phonate SI in 70% overall radiochemical yield. Homer—Wadsworth—Emmons reaction with the corresponding aldehyde derivative and reduction of the resulting a,/3-unsaturated ketone converted 81 into 82". ... 

Fyrol 76 is a vinylphosphonate/methylphosphonate oligomer and is water soluble. It was developed by Dr. Edward Weil and his group (22,25). It is prepared by the thermal condensation of bis(2-chloroethyl) vinylphosphonate with dimethyl methyl-phosphonate as shown in the idealized equation 29. 

Formylation of dimethyl 1 -(methoxycarbonyl)methylphosphonate with methyl formate under basic conditions using MeONa/MeOH results in the quantitative formation of the sodium enolate. An alternative procedure is the preparation of masked aldehydes by reaction of tert-butoxy-Z T(dimethylamino)methane or ATV-dimcIliyllonnarnidc dimethyl acetal with diethyl 1-(ethoxycarbonyl)methylphosphonate. The former reacts at 160°C for 3 h with diethyl l-(ethoxy-carbonyl)methylphosphonate to give the corresponding enaminophosphonate in 72% yield, whereas the use of the latter increases reaction yields (82-95%) and rates (2 The subsequent... 

The t3q)ical procedure for the preparation of optically active 0,0-dimethyl [1-(substituted phenoxyacetoxy)- -(substituted phenyl)]methylphosphonates (Scheme 9.33) is described as follows. 

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