Phosphonates, arylation

DNBLeu (covalent).5 Chiral phases S-Asp-artyl-S-phenylalanine methyl ester, N.N- Di-propyl-S-alanine cupric acetate. Phosphonates, aryl-sulphoxides, nitrogen heterocycles, di-B-naphthols. 

Aromatic Alcohols Aromatic Amino Acids Aromatic Amino Alcohols Aromatic Thiols Aromatic Amines Aromatic Sulfoxides Mandelic Acid Analogs Aryl-Substitute Phthalides Aryl-Substituted Lactams Aryl-Substituted Succinimides Aryl-Substituted Hydantoins a-Hydroxy-a-Aryl Phosphonates Aryl Propionic Acids Phenoxy benzy 1 amine s (P-Blockers)... 

Alkyl or aryl phosphonates, which contain a carbon—phosphoms bond, are comparatively more stable. They are of interest as antiscaling additives and corrosion inhibitors for cooling towers and heat exchangers (see Dispersants Water, industrial water treatment), surfactants (qv), sequestrants, and textile-treating agents. Trialkyl phosphites are usehil as esterification (qv) reagents. 

Phosphoms compounds are effective flame retardants for oxygenated synthetic polymers such as polyurethanes and polyesters. Aryl phosphates and chloroalkyl phosphates are commonly used, although other compounds such as phosphonates are also effective. The phosphoms compounds can promote char formation, thereby inhibiting further ignition and providing an efficient thermal insulation to the underlying polymer. 

Trialkyl esters of phosphonic acid exist ia two structurally isomeric forms. The trialkylphosphites, P(OR)2, are isomers of the more stable phosphonates, 0=PR(0R)2, and the former may be rearranged to resemble the latter with catalytic quantities of alkylating agent. The dialkyl alkylphosphonates are used as flame retardants, plasticizers, and iatermediates. The MichaeUs-Arbusov reaction may be used for a variety of compound types, including mono- and diphosphites having aryl as weU as alkyl substituents (22). Triaryl phosphites do not readily undergo the MichaeUs-Arbusov reaction, although there are a few special cases. 

ARBUZOV MICHAELIS Phosphonale Synihesis Ni catalyzed phosphonate synthesis from phosphites and aryl halides Reaction of alkyl halides with phosphites proceeds without nickel salts... 

A multitude of 1,4-dicarbonyls (1) undergo the Paal-Knorr reaction with and ranging from H to alkyl, aryl, carbonyl, nitrile, and phosphonate, while R and R vary between H, alkyl, aryl, trialkylsilyl, and O-alkyl. Protic acid catalysts are typically used with sulfuric, hydrochloric, and p-toluenesulfonic acids the most popular. Conversion to the furan takes place either at room temperature or upon heating with reaction times varying from five minutes to 24 hours and yields ranging from 17-100%. 

A multitude of 2,3,5-trisubstituted furans are available via the Paal-Knorr condensation. As with the synthesis of disubstituted furans, the scope of this version of the reaction is broad and includes incorporation of aryl, alkyl, ester, and phosphonate substituents. 

Examples of the intermolecular C-P bond formation by means of radical phosphonation and phosphination have been achieved by reaction of aryl halides with trialkyl phosphites and chlorodiphenylphosphine, respectively, in the presence of (TMSlsSiH under standard radical conditions. The phosphonation reaction (Reaction 71) worked well either under UV irradiation at room temperature or in refluxing toluene. The radical phosphina-tion (Reaction 72) required pyridine in boiling benzene for 20 h. Phosphinated products were handled as phosphine sulfides. Scheme 15 shows the reaction mechanism for the phosphination procedure that involves in situ formation of tetraphenylbiphosphine. This approach has also been extended to the phosphination of alkyl halides and sequential radical cyclization/phosphination reaction. ... 

The results presented in this review concern this metal-catalyzed mechanism. Depending on the nature, anionic or neutral, of the different nucleophiles, the result of the arylation can be a neutral substitution product or a cationic one, which most often, in the last case, undergoes an evolution, for example (starting form a phosphite) to a phosphonate or, after deprotonation, to an arylamine or to an arylether (Fig. 2). 

Examples of cyclic aliphatic or aryl phosphonate triesters, such as 36 or 37 have also been prepared by this HHT method from their cyclic phosphite precursors (2). 

In contrast, when excess amounts of the HHTs derived from simple aliphatic glycinate esters, such as 25, were used in excess in reactions with diaryl phosphites (SO), the related glyphosate aminals containing aryl phosphonate esters 46 were isolated in low yield (5-15%). Like many aminals, these triesters 46 were acid-sensitive and were quantitatively converted to the corresponding triester strong acid salts 47 upon treatment with either HCl or methanesulf onic acid (27). 

Reduction of halophosphines [34-37] or alkyl phosphonates [38] using lithium aluminum hydride is commonly employed for the preparation of alkyl or aryl substituted primary phosphines (Eqs. 1-4) ... 

Among /1-thiosubstituted organophosphorus compounds bearing chiral groups, phosphono methyl thiazolines (Sect. 2.2.1, Scheme 8) and o-sulfanyl aryl phos-phonamides or phosphinoxides (Sect. 3.3, schemes 20 and 21) have already been mentioned. As a complement to this, some recent synthesis of non racemic /1-sulfinyl phosphines and phosphonates and thiazolidinyl phosphonates are reported below. Moreover, some chiral )8-thio-substituted phosphines have been used as metal ligands in asymmetric catalysis and are listed in Sect. 5.3. 

Dielectric relaxation studies of phosphorylated polyethers from — 180° to 200 °C have been used to study their structures. The magnitude of the dielectric constants of high-phosphonic-acid-content polymers is much larger than predicted, which suggests a microphase-separated structure. Conductance studies on some aryl- and alkyl-phosphonium salts showed a higher conductance for the halides than for the nitrate. ... 

Et or Bu) and the phosphonation of iodoaromatics with dialkyl phosphonates, although in this case with poorer yields (better results of the dialkyl arylphosphonates are obtained by photostimulation). Chemical oxidation (using AgNO -peroxodi-sulphate) and anodic oxidation of aromatics in the presence of trialkyl phosphites produces dialkyl arylphosphonates in good yields. The Cul-catalysed arylation of dialkyl (cyanomethyl)-phosphonates affords dialkyl (a-cyanobenzyl)phosphonates. ... 

E NSF is a useful reagent for the low temperature conversion of the (hydroxyalkyl)phosphonic esters (88 X=OH R=allyl, or aryl) and (89.) into the corresponding (fluoroalkyl) phosphonic... 

Diethyl arylphosphonates were synthesized by reactions of diethyl phosphonate with aryl iodides or bromides containing electron-donor or electron-acceptor substituents in the aromatic ring in aqueous MeCN or neat H2O in the presence of Pd complexes with water-soluble ligands.34 For example, MeCN/H20 (1 mL), PhBr (8.2 mmol), and Ph2P(C6H4S03Na-m) (approximately 0.4 mmol) were successively... 

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