Dialkyl phosphites diethyl phosphite

Another method for the preparation of hydroxyalkanephosphonic acids is the conversion of aldehydes with dialkyl phosphites in the presence of triethylamine or sodium methylate leading directly to the corresponding a-hydroxyalkane-phosphonates. This reaction is reversible, leading to the starting materials aldehyde and diethyl phosphite again [143,146]. 

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) ... 

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. 

Preparation of diethyl (S)-a-hydroxybenzylphosphonate — Reaction of an aldehyde with a dialkyl phosphite facilitated by a chiral BINOL complex... 

Preparation of diethyl phenylphosphonate — Reaction of an aryl halide with a dialkyl phosphite in the presence of a Pd(0) catalyst and a tertiary amine... 

Preparation of diethyl pyridine-2-phosphonate — Reaction of an N-methoxy pyridinium salt with a dialkyl phosphite salt... 

Preparation of diethyl (Z)-l-propenylphosphonate — Reaction of a vinylic bromide with a dialkyl phosphite catalyzed... 

Preparation of diethyl 3,3-diethoxypropynyl-l-phosphonate — Reaction of a sodium salt of a dialkyl phosphite with an acetylenic halide492... 

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

Published data on the reaction of isatin with di- and trialkyl phosphites are somewhat contradictory. In particular, the authors in [78] showed that isatin with trialkyl phosphite forms 2 1 adduct, which has the structure of 1,3,2-dioxaphospholane containing a pentacoordinated phosphorus atom. More recently analogous results were obtained in the reaction of isatin with amidophosphites [79], At the same time it was shown [80] that 5-methylisatin reacts with trialkyl phosphites with the formation of 3-dialkoxyphosphoryl-3-hydroxy-2-indolinones, identical with the compounds obtained in the reaction of isatin with dialkyl phosphites [78]. In the monograph [4] with reference to the patent [61] the reaction of diethyl phosphite with isatin under the conditions of the Abramov reaction was indicated to lead to 3-dialkoxyphosphoryl-2-indolinone. In all probability this needs verification. 

Potassium dialkyl phosphite ions react rapidly with aryl iodides in liquid ammonia under irradiation to form diethyl esters of arylphosphonic acid in almost quantitative yields238. The photostimulated reaction of (EtO)2PO ions with 5-chloro-7-iodo-8-isopropoxyquinoline gave 70% of the substitution product with retention of the 5-chloro substituent239. The same nucleophile was formed in THF, and in a mixture of solvents (1 4 THF MeCN) reacts under irradiation with ArX (o-, ra-,/ -iodoanilines, 2-iodo, 3-iodo, 2-bromo and 3-bromopyridines and 3-bromoquinoline) rendering the substitution product in high yields (70-98%) (equation 130)240. 

Carbohydrate moieties have also been used as chiral auxiliaries in the addition of dialkyl phosphites to the C = N bond. Thus, 0-pivaloylated iV-benzylidene-/ -D-galactosylamine reacts with diethyl phosphite to give four diastereomeric esters (the a and (i forms not shown), in which those with the S configuration at the newly created stereogenic center prevail69. 

Abstraction of positive halogen by trivalent phosphorus compounds represents an expeditious route for the synthesis of dialkyl l-(trimethylsilyl)methylphosphonates. Thus, treatment of diethyl trichloromethylphosphonate with hexamethylphosphorous triamide (HMPT) in the presence of McjSiCl in CgHg at room temperature affords diethyl l-(trimethylsilyl)-l,l-dichloromethylphos-phonate in 90% yield. Similarly, CCI4 and CICI3 have been reacted with trimethylsilylmethyl dialkyl phosphites. ... 

Conant, J.B.. and Coyne, B.B., Addition reactions of the phosphorus halides. Part 5. The foimation of an unsaturated phosphonic acid, J. Am. Chem. Soc., 44, 2530, 1922 Chem. Abstr., 17, 273a. 1923. Gajda. T.. A convenient synthesis of diethyl 1-chloroalkylphosphonates, Synthesis, 111, 1990. Pudovik, A.N.. Zimin, M.G., and Sobanov, A.A., Reactions of dialkyl phosphites withketones activated by electronegative groups, Zh. Obshch. Khim., 42, 2174. 1972 Chem. Abstr., 78, 58543, 1973. Johnson. R.A.. Aryhnethylphosphonates and phosphonic acids useful as anti-inflammatory agents, their preparation, and their activity, Upjohn, U.S. Patent Appl. US 5500417, 1996 Chem. Abstr. 124. 307587. 1996. 

The reaction proceeds on heating dialkyl phosphites with a-chloroketones for a long time at 100-165°C with a catalyst (MeONa/MeOII) or at 100-120°C without catalyst, and with chloroacetaldehyde at 100°C without catalyst to give, in 50-100% yields, the chlorohydrinphos-phonates having the hydroxyl group in the a-position. The reaction between diethyl phosphite and chloroacetaldehyde can also proceed at room temperature in the presence of a catalytic amount of EtjN.si... 

The preparation of dialkyl phenylphosphonates by the coupling of aryl bromides or iodides with dialkyl phosphites in the presence of Ft,N and a catalytic amount of Pd(PPh3)4has been exploited for the synthesis of diethyl pzzzzz-l onnylpheiiylphosphonate. The para-bromobenzaldehyde has to be protected as its 1,3-dioxolane to allow an efficient coupling with diethyl phosphite (Scheme 5.44). ... 

A report of the synthesis of thermodynamically stable ( )-vinylphosphonates from diethyl 1-formyl-l-phenylalkylphosphonates by a Homer-Wadswoilh-Ermnons-type reaction has appeared. Sodium P-hydroxyphosphonates, generated by the reaction of sodium dialkyl phosphites with... 

Ring opening of diethyl 1,2-epoxyalkylphosphonates by refluxing ethanolic solutions of sodium dialkyl phosphites proceeds by attack at the P-carbon atom of the epoxide via the sodium phos-phite-alcoholate equilibrium. For example, diethyl 1-methyl-1,2-epoxypropylphosphonate undergoes ring opening by sodium dialkyl phosphites with concomitant elimination of dietliyl phosphite to afford dialkyl l-methyl-2-oxopropylphosphonates in reasonable yields (Scheme 7.47). ... 

At room temperature, diethyl l-phenyl-2-oxoalkyIphosphonates undergo attack at the carbonyl by sodium dialkyl phosphites in THF to give transient hydroxyphosphonates, which eliminate sodium diethyl phosphate according to a Homer-Wadsworth-Emmons-type reaction to provide stable dialkyl ( )-l-phenylalkeny Iphosphonates in moderate to good yields (20-94%) (Scheme 7.112). The elimination is favored by the presence of the phenyl group. ... 

Unquestionably, one of the most attractive synthetic methods for the preparation of dialkyl 2-(alkoxycarbonyl)ethylphosphonates involves the conjugate addition of a dialkyl phosphite to the carbon-carbon double bond of a,p-unsaturated carboxylates (Pudovik reaction, Scheme 8.44). In the presence of EtONa, diethyl phosphite reacts vigorously with acrylate in EtOH to give the Michael addition product in 84% yield. The reaction is applied with success to the synthesis of dialkyl 2-(alkoxycarbonyl)ethylphosphonates bearing a large variety of acyclic (symmetric - or disymmetric 30 or cyclic (symmetric or disynunetric ) substituents at phosphorus. 

Evidence has been presented which appears to support an earlier hypothesis regarding the reaction between sodium dialkyl phosphites and polyhalogeno - methanes according to this, the phosphite salt and bromotrifluoromethane yield (difluoromethylene)bisphosphonic tetraesters through the abstraction of the bromonium cation by the phosphite anion, and this is followed by phosphorylation of the subsequent carbanion. The present evidence is based on the treatment of diethyl (dichlorofluoromethyl)phosphonate with sodium diethyl... 

This reaction is. a welcome expansion of the base-catalysed addition of dialkyl phosphites which fails with sterically hindered olefins and with unsaturated aldehydes occurs at the carbonyl group. An example of the efficiency of the method with sterically hindered alkenes is afforded by the reaction of mesityl oxide which leads to diethyl (1, l-dimethyl-3-oxobutyl)phosphonate 7 0... 

The phosphorous diester is usually used as sodium salt. The oldest technique is to treat the dialkyl phosphite with an equivalent amount of sodium291 in an inert solvent (toluene, xylene, dioxan, tetrahydrofuran, or ether) before adding the alkyl halide. Dibutyl phosphite has the advantage over the more frequently used diethyl phosphite that its sodium salt is soluble in hydrocarbons.292 Complete conversion into the sodium salt requires several hours heating unless the metal is finely divided for the preparation of stable dis-... 

Although it might be expected that reactions which employed triarylmethyl halides would occur very readily, such reactions are rendered potentially more complex by the known nature of the halides and their propensity for involvement in free radical reactions. Whereas normal alkylation proceeds between sodium diethyl phosphite and diphenyl-methyl halides, success, or otherwise, in the use of the triphenylmethyl halides depends to some extent on the individual halide and on the metal in the phosphite salt. Thus, in an early study (in 1939), Arbuzov found that in reactions between silver dialkyl phosphites and triphenylmethyl bromide, dialkyl triphenylmethylphosphonates were indeed formed, but the use of the corresponding alkyl chloride provided the phosphite triester instead (metal dialkyl phosphites possess ambident anions ). A later study confirmed the behaviour of the silver salts towards the chloride, but also showed that, whereas dialkyl phophites with primary alkyl groups yielded phosphonic diesters (as had already been found), those with secondary alkyl groups afforded phosphite triesters moreover, the presence and nature of aromatic substituents were also able to control the course of the reaction. Reactions which involve triarylmethyl halides and sodium dialkyl phosphites may well be of a free radical nature since repeated studies have demonstrated the forma-... 

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