Phosphorus, reaction with alkyl halides

These reactions may be considered to be a method of obtaining 1,3,2,5-dioxaborataphosphoniarinanes with different substituents at carbon and phosphorus atoms of the ring. Comparing the properties of cyclic oxyalkyl-phosphines and boryloxyalkylphosphines, it should be noted that in both cases the reaction with alkyl halides results in the formation of a tertiary phosphonium salt. The reaction with electrophilic reagents such as diphe-nylchlorophosphine and diphenylchloroborane proceeded quite differently [Eq. (100)]. 

Several methods for the preparation of the parent compound in this system, tris(trimethylsilyl)phosphite, have been reported.114 118 The application of this and related reagents in reaction with alkyl halides has been reported and used for the preparation of a variety of phosphonic acid analogues of phospholipids.114119-124 Interestingly, alkyl chlorides appear to be more reactive with the silyl reagents than do alkyl iodides, a reversal of the normally observed trend with alkyl esters of the phosphorus acids. (The particular use of silyl phosphorus reagents for the synthesis of biologically significant compounds has... 

In the dissertation [11] amidophosphite 3d was brought into reaction with alkyl halides. In the 31P NMR spectrum the obtained quaternary salts 57 give a signal in the region of 51-54 ppm, characteristic of a quatemized phosphorus atom. The acid hydrolysis of the salts 57 leads to the previously described [49] 3-indolylphosphonic acid (56). 

Reactions with Alkyl Halides.— The in situ generation and reaction of chlorodi-phenylphosphine (2) with a-chloro-ethers gives good yields of a-alkoxyalkylphosphine oxides (20). The phosphine (2) is made from phosphorus trichloride and benzene, and the sequence looks like a very convenient one-pot procedure - the dangers of certain chloro-ethers aside ... 

Stelzer and co-workers reported a number of chiral water-soluble secondary phosphines [14], prepared by nucleophilic phosphination of primary phosphines with fluorinated aryl sulfonates in the superbasic medium DMSO/KOH. Further reaction with alkyl halides gives bidentate tertiary phosphines with P-chirality, but only racemic versions have been reported so far. Hanson et al. introduced so-called surface-active phosphines into asymmetric aqueous-phase catalysis. One of the main problems inherent to two-phase catalysis is the often very low miscibility of the substrates in the aqueous phase. Insertion of long alkyl chains between phosphorus atoms and phenyl groups in sulfonated phosphine ligands has been proven to increase reaction rates in the Rh-catalyzed hydroformylation of 1-octene [15], This concept was extended to a number of chiral ligands, i.e., the monoden-... 

The anions (118) are formed by the addition of alkali metals to 1-phenylphospholes. Protonation of the anions gave phosphorus-unsubstituted phospholes, reaction with alkyl halides afforded the phospholes (119), and subsequently the phosphonium salts (120). 

Under more forcing conditions, sulphur analogues [e.g. EtSPEt2] of tervalent phosphorus acids also undergo the Arbusov reaction with alkyl halides. ... 

Kosolapoff (182), who prepared tri- cr -butyl phosphite from phosphorus trichloride and er -butyl alcohol, claimed that This phosphite could not be made to undergo the Michaelis-Arbuzov reaction with alkyl halides at temperatures under 80-90°, while above that temperature it began to decompose with evolution of isobutylene. Further support for the concept that the tertiary ester group is unreactive was provided by the... 

B. By Hydrolysis Reactions.—Details have appeared of the synthesis of dibenzophosphorin oxides (15) from 5-alkyldibenzophospholes, by reaction with methyl propiolate in the presence of water, and of confirmatory syntheses from phosphinic acid chlorides, as shown below. Evidence for the suggested mechanism of the ring-expansion reaction is presented. The hydrolysis of enamine phosphine oxides is an efficient, although somewhat indirect, method for the preparation of j8-ketoalkylphosphine oxides (16) [see Section 3(iii), for the preparation of enamine oxides]. Reasonable yields (48—66%) of trialkylphosphine oxides (17) have been obtained by the alkaline hydrolysis of the products from the pyrolysis at 220 °C of red phosphorus with alkyl halides, in the presence of iodine. 

A. Nucleophilic Reactions of the P=0 Group.—Tris(trifluoromethyl)-phosphine oxide (33) reacts with hexamethyldisiloxane to give a phos-phorane, whose n.m.r. spectrum at — 140 °C shows non-equivalent trifluoromethyl groups. Although this unusual reaction clearly involves nucleophilic attack of the phosphoryl oxygen on silicon at some stage of the reaction, a full study of the mechanism has not been published. Tertiary phosphine oxides can be converted cleanly into dichlorophos-phoranes (34) by treatment with two moles of phosphorus pentachloride. Alkylation of the sodium salt of tetraphenylmethylenediphosphine dioxide (35) with alkyl halides, in dimethyl sulphoxide, has been reported to... 

Trippett and Stewart have shown that the phosphonium salts (11) derived from the reaction of phenyl di-t-butylphosphinite (12) with alkyl halides are highly resistant to hydrolysis and they suggest that this is due to the reluctance of phosphorus to accommodate two t-butyl groups in a trigonal-bipyramidal intermediate. 

The reaction of a trialkyl phosphate with an alkyl halide to produce an alkyl phosphonate. The first step involves nucleophilic attack by the phosphorus on the alkyl halide, followed by the halide ion dealkylation of the resulting trialkoxyphosphonium salt. 

Alcohols and phenols are also weak bases. They can be protonated on the oxygen by strong acids. This reaction is the first step in the acid-catalyzed dehydration of alcohols to alkenes and in the conversion of alcohols to alkyl halides by reaction with hydrogen halides. Alkyl halides can also be prepared from alcohols to alkyl halides by reaction with hydrogen halides. Alkyl halides can also be prepared from alcohols by reaction with thionyl chloride or phosphorus halides. 

Reactions of vinylphosphonates j2 with an equimolar amount of lithium dialkylcuprates J result in the formation of complexes 3 containing two different organic ligands. These complexes react with electrophiles in various ways. In each of them a diverse ligand plays the role of a nucleophile. Hydrolysis of 3 or alkylation with alkyl halides affords the corresponding phosphonates k and 5 comprising extended saturated carbon chains bonded to phosphorus. However, in a number of reactions with aldehydes, the complexes 3 were found to undergo almost completely selective transformation into carbinols 6... 

Thieno[2,3-c]isothiazole-3-carboxylic acid was the compound obtained by the reaction of ethyl 3-cyano-5,5-diethoxy-2-oxopentanoate with phosphorus pentachloride in refluxing toluene, previously assumed (55JA4069) to yield thieno[3,4-c ]isothiazole-4-carboxylic acid. The proposed mechanism involves the cyclization of the intermediate 3-cyano-2,5-dithioxopentanoate as shown in Scheme 20. The parent heterocycle, which is a weak base and fails to give quaternary salts with alkyl halides, was obtained by decarboxylation of the acid and also by independent synthesis (82AJC385). 

A publication discussing the uses of reactive arsonium ylides for the stereospecific preparation of epoxides draws attention to the fact that arsonium salts are less readily prepared than phosphonium salts because of the poorer nucleophilicity of arsenic compared to phosphorus, and suggests methods for obtaining them. Primary salts were made from alkyl triflates, while a-branched salts were prepared from alkyldiphenylarsines, obtained from iodo compounds as, for example, in equation 23. Reaction of alkyl halides with arsines to form arsonium salts is also promoted by the presence of silver tetra-fluoroborate . 

Since reaction of phosphorus with alkyl halides occurs also without a catalyst, direct attack by the alkyl halide must be possible. Support that these reactions are also radical in nature has been provided by the work of Petrov, Smirnov, and Emel yanov In the reaction of white phosphorus with Cg H5 CH2 Cl ), PhBr ) ff2-CH3C6H4Br and n-CgHi7Br in the liquid phase phosphonous dihalides are the predominant products but appreciable yields of phosphi-nous halides are also obtained. A correlation was observed between the tempera-... 

A new approach to the synthesis of dialkylamino-alkylphosphines consists in the reaction of white phosphorus with dialkylaminolithium compounds followed by treating the reaction mixture with alkyl halide for example (CH3)2NP ( 3)2... 

Phosphorus ylides are prepared from a nucleophilic substitution reaction between alkyl halides and triphenylphosphine (PPh3). The resulting alkyltriphenylphosphonium salt is then deprotonated by reaction with a strong base (e.g. BuLi) to form the ylide. 

Further, elemental phosphorus can be converted by Grignard reagents or organolithium compounds into metal phosphides which afford primary phosphines on hydrolysis phenylphosphine was obtained in this way in yields of up to 40% from phenyllithium and white phosphorus.214 In some circumstances cyclophosphines are formed on reaction of alkyl halides with the phosphide solutions obtained from elemental phosphorus.215... 

Halophosphines are produced by reactions of phosphorus with alkyl chlorides, alkyl bromides, or aryl bromides in solution (12) and by reaction of red phosphorus in tlie presence of copper with alkyl halides in tlie vapor phase (13). Both methods require temperatures in excess of 2 )0°. The preparation of halopliosphines in solution is illustrated by the results of uncatalyzed white phosphorus reactions summarized in Table I (12). Alkyl dihalopliosphiues are the predominant products under these conditions, but appreciable yields of dialkylmonohalophos-phines are also obtained. The reaction temperature requirement de-... 

In fact, lithium diphenylphosphide can be reacted in situ with alkyl halides to give phosphines. Obviously, this reaction could be a serious side reaction in mixtures obtained from lithium reagents and phosphorus trichloride in which residual lithium was present. It should be noted also that metalation of triphenylphosphine with butyllithium occurred at the meta position on one ring to a small extent (58). Consequently, in the condensation of phosphorus halides with lithium reagents prepared by an exchange reaction employing butyllithium, an excess of the latter could result in mixtures. 

One might expect that a phosphorus reagent having for R an aryl group activated for bimolecular nucleophilic substitution (68) by electron- withdrawing substituents might participate in a Michaelis-Arbuzov reaction. Kamai and Koshkina (159), who prepared a number of chloro-and nitro-substituted derivatives of triphenyl phosphite, found this to be the case for both ortho and para isomers of tris(monochlorophenyl) phosphite, which reacted with alkyl halides to furnish phosphonates. On the other hand, tris(2,4,6-trichlorophenyl) phosphite and tris(2,4-dichlorophenyl) phosphite (155) gave only complexes with methyl iodide however, lower reaction temperatures were employed. 

Closely related to the alkyl exchange reaction is the well-known formation of pyrophosphate esters from the interaction of pentavalent phosphorus esters with phosphoryl halides (296). 

The iV-propargylaminophosphines (78) readily rearrange to give the azabuta-dienylphosphine (79) via intramolecular nucleophilic attack of phosphorus at the terminal acetylenic carbon. Full details have now appeared of the reactions of 2 -1,2,3-diazaphosphole derivatives (80) with alkyl halides, giving 2,3-disub-stituted indoles as the major product. Several examples of the attack of phosphines at carbon of a, -unsaturated carbonyl compounds have been described. The betaine (81) is the active intermediate in the triphenylphosphine-induced polymerization of maleic anhydride. Phosphines also catalyse the... 

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