Alkylphosphinate esters

A divergent synthesis of both diastereoisomers of ( )-(3-aminocyclopentane)alk-ylphosphinic acid (180) gave conformationally restricted analogues of GABA. Both diastereoisomers were obtained in 5 steps from the key ( )-(3-hydroxycyclopent-l-ene)alkylphosphinate esters (181) which were prepared via a palladium catalysed C-P bond forming reaction (Scheme 61). 

COi is another molecule which reacts with conjugated dienes[10,95,96], COt undergoes cyclization with butadiene to give the five- and six-membered lactones 101. 102. and 103, accompanied by the carboxylic esters 104 and 105[97.98], Alkylphosphines such as tricyclohcxyl- and triisopropylphosphine are recommended as ligands. MeCN is a good solvent[99],... 

In the presence of a base such as l,4-diazabicyclo[2.2.2]octane (DABCO) or tri-alkylphosphines, conjugated carbonyl compounds such as esters and amides add to aldehydes via the a-carbon to give a-alkenyl-P-hydroxy esters or amides. This sequence is called the Baylis-Hillman reaction and a simple example is... 

The reactions of dimethyl phenylphosphonite with acid chlorides, a-halogeno-ketones, and iV-(bromomethyl)phthalimide have been used to prepare acyl phos-phinates, /3-keto-alkylphosphinates, and phthalimidomethylphosphinates as intermediates in the synthesis of a-diazophosphinic esters.39 a-Amino-phosphonates have also been prepared by the addition of secondary phosphites to nitriles40 and to isocyanides.41... 

ALKYLHALOPHOSPHINES, ALKYLPHOSPHINES tert-BUTYL PEROXOPHOSPHATE ESTERS iV-CHLORINATED PHOSPHORUS AMIDES HALOPHOSPHINES, METAL PHOSPHINATES METAL PHOSPHORUS TRISULFIDES NON-METAL OXIDES, NON-METAL SULFIDES PHOSPHINES, PHOSPHORUS ESTERS... 

In separate experiments, we have demonstrated that TPO also promotes hydrogenolysis by Ru ( 7), although the effects are weaker than for the Rh-catalyzed hydrocarbonylation of esters. The use of alkylphosphine oxides and their role in Ru-catalyzed syngas reactions have also been reported by Warren and Dombek (8b). 

A variety of activated carbonyls such as a-keto esters, benzils, cyclohexane-1,2-dione, and a-ketophosphonates have been reduced to the corresponding a-hydroxy compounds in THF at room temperature, using alkylphosphines (PMe3 or PPhMe2).335... 

The unsaturated character of these trialkyl esters was shown by the ease with which they were attacked by nitric acid, but still more clearly by the formation, with evolution of heat, of stable crystalline addition compounds when they were mixed with cuprous halides. Thus CuC1.P(OC2H5)3 was described as consisting of colourless crystals melting at 190° to 192° C. and soluble in organic solvents.4 This property they share with phosphine, alkylphosphines and phosphorus trihalides. The phosphoric esters were quite indifferent to cuprous halides. Nor were such addition compounds formed either by phosphorous acid itself or by the dialkyl esters, which may show that the latter compounds have the unsymmetrical formula. Phosphorous acid probably exists in both forms, but first as P(OH)3, i.e. when produced from PC13 and Ha0.5 This may be transformed into the unsym-metrieal form through an addition compound HC1.P(0H)3,4 and probably also exists in the form of complex molecules, such as... 

R2POH [R2P(0)H] Phosphinous acid (alkylphosphinous acid esters alkyl dialkylphosphinite) phosphinige Satire... 

One of the cleanest and most general reactions undergone by trivalent phosphorus compounds occurs with sulfur (177). For example, tri-alkylphosphines react vigorously with sulfur to yield trialkylphosphine sulfides. The analogous reaction of phosphorus esters has received considerable attention as a synthetic method, due largely to the insecticidal potency of the phosphorothioate esters. 

The procedure has been adopted for the preparation of alkyl dialkylphosphinates from alkyl alkylphosphinates (monoalkyl alkylphosphonites) as depicted in equation 21 and of the bisphosphinic esters and acids 109 ( = 1 or and 110. ... 

Phosphonium salts manufactured by the above metathesis route will typically contain a few ppm of halogen anion. In many cases, this may be irrelevant, but if a totally halogen-free salt is required, they can readily be prepared in a simple one-pot procedure by heating a tertiary alkylphosphine with a tosylate, sulfate, or phosphate ester [51,59,60[. Examples are triisobutyl(methyl)phosphonium tosylate (CYPHOS IL 106),tributyl(methyl)phosphoniummethylsulfate (CYPHOS IL 108), and tributyl(ethyl)phosphonium diethylphosphate (CYPHOS IL 169). 

As has already been mentioned in the discussion of metallic salts of organic and inorganic acids, the acid radicals of such stabilizers can represent esters of phosphoric or alkylphosphinic acids. In addition to salts of alkylphosphinic acids, the use of sodium, aluminum, barium, and calcium salts of aliphatic esters of phosphoric acid is recommended [291]. 

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