Diethylphosphite

A recent paper [44] shows that the treatment of silyl thioketones 68 with lithium diethylphosphite proceeds via a thiophiUc attack followed by a thio-phosphate mercaptophosphonate (69 70) carbanionic rearrangement and the migration of the silyl group from the carbon to the sulfur atom leading to the S-silylated sulfanylphosphonate carbanion 71. The last step represents the first example of the thia-Brook rearrangement (Scheme 18). 

Materials and Purification. Chemicals were purchased from Aldrich chemical company and used as received unless otherwise noted 1,1,1,3,3,3-hexamethyl disilazane, ethylene glycol, triphosgene, poly(ethylene oxide) (MW = 600), poly(tetramethylene oxide) (MW = 1000), poly(caprolactonediol) (MW = 530), toluene diisocyanate (TDI), anhydrous ethanol (Barker Analyzed), L-lysine monohydride (Sigma) and methylene bis-4-phenyl isocyanate (MDI) (Kodak). Ethyl ether (Barker Analyzer), triethylamine and dimethyl acetamide were respectively dried with sodium, calcium hydride and barium oxide overnight, and then distilled. Thionyl chloride and diethylphosphite were distilled before use. 

Synthesis. Bis(2-hydroxyethyl)phosphite was synthesized by adopting the procedures described by Borisov and Troev (6). Briefly, a molar ratio of 4 1 of ethylene glycol (73 mL 1.3 mole) to diethylphosphite (43 mL 0.33 mole) was placed in a round bottom flask equipped with a reflux condenser and a thermometer. A two mL fresh solution of sodium methoxide was added dropwise through a dropping... 

Pd-catalyzed C—P bond formation on the benzene ring of quinoxaline has been reported. Phosphoric acid ester 102 was prepared from 7-bromoquinoxaline 101 and diethylphosphite via a Heck-type reaction [59],... 

Fig. 16 Examples of current dips (a) 2-iodoquinoline (1.6 mM) with benzenethiolate ions (44 mM) (b) 2-iodoquinoline (5.2 mM) with diethylphosphite ions (100mM). Scan rate, 0.2Vs . Example of trace crossing (c) 4-chlorobenzonitrile (1.55mM) with diethylphosphite ions (663 mM). Scan rate, 0.215 Vs . In liq. NHj/O.l m KBr at — 40°C. (Adapted from Amatore et a ., 1980a,b.)...

It is shown (Bunnett and Shafer 1978) that the prodncts of thiophenolate and diethylphosphite disnbstitntion do not form from monosnbstituted derivatives. The monosubstituted prodnct is 20 times less active than the initial substrate with regard to thiophenolate. The S nI model takes all these facts into consideration (see Scheme 4.17). 

Scheme 36 Fast palladium-catalyzed phosphonation using diethylphosphite...

The photoinitiated reaction of diethylphosphite ion with iodobenzene has been examined in different solvents [60]. The reaction of acetone enolate ion with 2-chloroquinoline, under the same irradiation times, suffers a strong dependence on solvent nature. Thus, the yield of substitution product decreases going from liquid ammonia (90%) to THF (82%), DMF (74%), dimethoxyethane (28%), diethyl ether (9%), or benzene (4%) [61]. For this reason, the reactions are usually performed in liquid ammonia or DMSO under irradiation. 

In the first case the deiodination was brought about by the use of zinc and ultrasound109 however in other cases the use of a dialkyl phosphite and sodium hydride at 20 °C also provides a very mild and efficient method110. In the last case, both cis- and /ww-di-iodides reacted at similar rates, but while the cis-isomer reacted also with the related reagent diethylphosphite and triethylamine to give the cyclopropene in 20 h at 20 °C, the trans-isomer remained largely unchanged under these conditions. 

Under similar conditions, the same authors performed the addition of diethylphosphite to aldehydes and ketones (a Pudovik-like reaction) and to Michael acceptors such as imines, acrylonitrile and a,B-unsaturated ketones3b to give functionalised phosphonates (Figure 3). 

Add the lithium diethylphosphite solution to the imine 50 solution via a cannula and stir the resultant mixture at room temperature for 20 h. 

The reaction of oxazolines (331) derived from L-serine with diethylphosphite leads to a mixture of racemic a- and p-phosphono alanines (332) and (333). This new reaction proceeds without the use of any halogenated intermediate, and offers a simple route for various phosphonoamino acids bearing suitable protecting groups (Scheme 89). " ... 

On the basis of this result, the C3 hydroxyl was replaced with phenylselenyl, phenysulfenyl, phenoxythiocarbonyl groups or bromine, and the C2 bromine was also replaced with fluorine, chlorine, or the diethylphosphite group. Schmidt s group demonstrated that, when the C3... 

A theoretical study of the intermediates involved in the formation of phospha-propyne from pyrolysis of vinylphosphirane has led to a new route to phospha-alkynes. Thus, pyrolysis of trimethylsilyl(l-phosphiranyl)diazomethane has yielded MeaSiC = P, via an intermediate 1-phosphiranylmethylene . Regioselec-tivity in the [3 + 2] cycloaddition reaction between phosphaethyne and diazomethane has been studied by theoretical techniques , and further examples of reactions of this type described . Cycloaddition of phospha-alkynes with silylenes has also been reported. The primary phosphine 324 has been isolated from the addition of diethylphosphite to t-butylphosphaethyne. The chemistry of phospha-alkyne cyclotetramer systems has been reviewed and the first examples of platinum(II) complexes of such cage systems described. Aspects of the reactivity of coordinated phospha-alkynes have received further study, and a remarkable metal-mediated double reduction of t-butylphosphaethyne to the complexed fluorophosphine 325 described Phosphorus-carbon-aluminium cage structures have been isolated from the reactions of kinetically stable phospha-alkynes with trialkylaluminium compounds and new phosphaborane systems have been obtained from the reactions of phospha-alkynes with polyhedral boranes . Further studies of wo-phospha-alkyne coordination chemistry have appeared . The reactivity of the ion 326 has been explored. ... 

An Sj l mechanism has been implicated in the photochemical reaction of diarylsulphides (and the corresponding sulphoxides and sulphones) with the enolate of pinacolone, and with diphenylphosphide anion and diethylphosphite anion.The products are derived from reaction of the anions with aryl radicals formed by cleavage of an aryl sulphur bond in a diarylsulphide radical anion intermediate. Thus (146) is formed from diphenylsulphide and the enolate of pinacolone. 

The best known phosphorus polyol of significant commercial importance is diethyl-N,N-bis (2-hydroxyethyl) aminomethyl phosphonate, which is obtained by a Mannich reaction between diethylphosphite, formaldehyde and diethanolamine (reaction 18.11) [5, 34] ... 

The same structure is easy to obtain by reacting diethylphosphite with an oxazolidine [16, 35] (reaction 18.12) ... 

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