Phosphite dimethyl

Another impo2rtant P—C-hond-forming reaction is the base-cataly2ed Michael addition to activated double bonds. For example, dimethyl phosphite can be added to dimethyl maleate to yield tetramethylphosphonosucciaate [2788-26-3] (TMPS), an iatermediate ia the synthesis of 2-phosphonobutane-l,2,4-tricarboxyhc acid [37971-36-1] (PBTC) with 98% yield (20). 

Preparation of (Me0)2P-0-R ROH, (MeO)3P, CBr4, Pyr, 70-98% yield. The alkyl dimethyl phosphite may then be oxidized to the corresponding phosphate by aq. iodine, t-butyl hydroperoxide, or peracid. 

The ring expansion of nitronaphthalenes with dimethyl phosphite and sodium methoxide in the presence of strong base to give 2-benzazepines (see Section 3.2.1.4.2.1.) has been adapted successfully to the synthesis of pyridoazepines, e.g. 24, 25, and 26, from 5-, 6-, and 8-nitro-quinoline, respectively43... 

The deoxygeneration of nitroarenes by trivalent phosphorus compounds in the presence of amines is a useful route to 3/f-azepin-2-amines (cf. compounds 32, Section 3.1.1.4.2.2.). Subsequently, it has been shown, by carrying out the reaction in strongly basic solution, that the process can be extended to the synthesis of 1H-. 3H- and 5//-2-benzazepines from nitronaph-thalenes 43 For example, 1-nitronaphthalenes 3 with dimethyl phosphite in the presence of sodium methoxide and a primary or secondary aliphatic amine, yield the dimethyl 5//-2-ben-zazepin-3-yl phosphonates 4 accompanied, in some cases, by the isomeric 3//-2-bcnzazepin-3-yl phosphonates 5. 

The presence of aldehyde groups in the macromolecules of modified PAN made it possible to obtain, as a result of an interaction with dimethyl phosphite at 120 °C, new PAN derivatives containing hydroxy-dimethoxyphosphorylmethyl groups according to the following scheme ... 

These phosphorus-containing PAN derivatives are unstable under hydrolytic conditions, and the phosphoryl groups are easily split off under the action of boiling water. If, however, the modified PAN is treated with dimethyl phosphite solution in toluene in the presence of dimethylamine, a modified PAN, stable towards hydrolysis, is obtained. Its composition seems to be the following ... 

P-coupling occurs in the formation of azophosphonic esters [ArN2PO(OCH3)2] from diazonium salts and dimethyl phosphite [HPO(OCH3)2] (Suckfull and Hau-brich, 1958). P-coupled intermediates are formed in the reaction between diazonium salts and tertiary phosphines, studied by Horner and Stohr (1953), and by Horner and Hoffmann (1956). The P-azo compound is hydrolyzed to triphenylphosphine oxide, but if a second equivalent of the tertiary phosphine is available, phenyl-hydrazine is finally obtained along with the phosphine oxide (Scheme 6-26 Horner and Hoffmann, 1958). It is likely that an aryldiazene (ArN = NH) is an intermediate in the hydrolysis step of the P-azo compounds. 

Spilling recently introduced various chiral diol ligands for Ti-catalyzed addition of dimethyl phosphite to cinnamaldehyde (Scheme 5-31). 

Kee reported using zinc catalysts for the addition of dimethyl phosphite to benzaldehyde (Scheme 5-42). 

Chiral aluminum SALEN complexes have been used by Kee for asymmetric addition of dimethyl phosphite to benzaldehyde derivatives (Scheme 5-43). 

A proposed mechanism (Scheme 5-44) begins with deprotonation of dimethyl phosphite to give an Al-phosphito complex (32) which can react with the aldehyde via either a chelate or open transition state, the latter possibly involving cooperative action of two aluminum centers, consistent with the observation of co-catalysis. Following P-C bond formation, several possible rearrangements could regenerate the achve catalyst and form the product... 

First, deprotonation of dimethyl phosphite accompanied by coordination of oxygen to the oxophilic lanthanide gives 33. Nucleophilic attack of P on the imine carbon along with N-coordination gives 34 proton transfer followed by product de-complexation regenerates the catalyst [33],... 

Scheme 5.9 illustrates some of the conditions that have been developed for the reductive deoxygenation of alcohols. Entries 1 to 4 illustrate the most commonly used methods for generation of thiono esters and their reduction by tri-M-butylstannane. These include formation of thiono carbonates (Entry 1), xanthates (Entry 2), and thiono imidazolides (Entries 3 and 4). Entry 5 is an example of use of dimethyl phosphite as the hydrogen donor. Entry 6 uses r .s-(trimethylsilyl)silane as the hydrogen atom donor. 

Penetration of dimethyl phosphite into the fibre, accompanied by decomposition of salt linkages and elimination of structural water in a multi-step hydration process. New salt linkages are formed between cationic groups in wool keratin and anionic dimethyl phosphite. 

Formation of covalent bonds between dimethyl phosphite, glucose and amino groups in wool keratin, stabilising the loosened fibre structure. 

R)-aluminum-lithium-BINOL complex (0.024 g, 0.04 mmol) was dissolved in toluene (0.4 ml), and to this solution was added dimethyl phosphite (0.044 g, 0.4 mmol) at room temperature the mixture was stirred for 30 min. Benzaldehyde (0.042 g, 0.4 mmol) was then added at -40°C. After having been stirred for 51 h at -40°C, the reaction mixture was treated with 1 N hydrochloric acid (1.0 ml) and extracted with ethyl acetate (3 x 10 ml). The combined organic extracts were washed with brine, dried over sodium sulfate, and concentrated under reduced pressure. The residue was purified by flash chromatography (silica, 20% acetone/hexane) to give the diethyl (S)-a-hydroxybenzylphosphonate (78 mg, 90%) with 85% enantiomeric excess as a colorless solid of mp 86 to 87°C. 

Ruveda, M.A. and deLicastro, S.A., Synthesis of dimethyl a-hydroxy phosphonates from dimethyl phosphite and phenacyl chloride and cyanide, Tetrahedron, 28, 6018, 1972. 

Butyllithium (23% in hexane) (63 ml, 0.15 mol) was added dropwise to diethyl phosphite (25 g, 0.18 mol) at -20 to -30°C over a period of 2 h. To the resulting mixture was added A/-methoxy pyridinium meth-osulfate in dimethyl phosphite (40 ml) over a period of 1 h at -15°C. The reaction mixture was stirred at room temperature overnight, and water (100 ml) was then added. The mixture was extracted with chloroform (3 x 75 ml), and the combined organic extracts were separated into neutral and basic fractions by extraction (4 N HC1), bas-ification, and reextraction with chloroform. The basic portion was distilled yielding diethyl pyridine-2-phosphonate (22.9 g, 67%) of boiling point (bp) 105-112°C/0.08 torr. 

Synonyms DMHP dimethoxyphosphine oxide dimethyl phosphite methyl phosphonate... 

Reactions with thiono esters, iodides, bromides, and selenides proceed efficiently with dimethyl phosphite or with hypophosphorous acid in the presence of a tertiary amine and AIBN.221... 

The product when, carefully distilled in CO2 usually exploded (Ref 5). A prepn from dimethyl phosphite, allyl alcohol ... 

B. Deoxygenation with dimethyl phosphite and related reagents 161... 

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