Triphenylphosphine oxide, alkyl

Wittig reactions are versatile and useful for preparing alkenes, under mild conditions, where the position of the double bond is known unambiguously. The reaction involves the facile formation of a phosphonium salt from an alkyl halide and a phosphine. In the presence of base this loses HX to form an ylide (Scheme 1.15). This highly polar ylide reacts with a carbonyl compound to give an alkene and a stoichiometric amount of a phosphine oxide, usually triphenylphosphine oxide. 

Mitsubishi has patented a triphenylphosphine oxide-modified rhodium catalyst for the hydroformylation of higher alkenes with both alkyl branches and internal bonds. [19] Reaction conditions are 50-300 kg/cm2 of CO/H2 and 100-150 degrees C. The high CO/H2 partial pressures provide stabilization for rhodium in the reactor, but rhodium stability in the vaporizer separation system is a different matter. Mitsubishi adds triphenylphosphine to stabilize rhodium in the vaporizer. After separation, triphenylphosphine is converted to its oxide before the catalyst is returned to the reactor. 

Compound 23 is the active alkylating agent. The a-carbon atom is acti ated toward nucleophilic attack, permitting it to alkylate the nitrogen of the deprotonated succinimide 5 to give TV-butenylimide 7. This releases triphenylphosphine oxide (Ph3P=0). Thus, in the overall process DFAD is reduced to hydrazine derivative 22, whereas triphenylphosphine is oxidized to triphenylphosphine oxide. 

Quaternisation of triphenylphosphine with an alkyl halide gives a quaternary phosphonium halide (4) which under the influence of a strong base eliminates hydrogen halide to give an alkylidenephosphorane [(5), an ylide]. The latter reacts with an aldehyde or ketone to give first an intermediate betaine (6), which rearranges to the oxaphosphetane (7), which then under the reaction conditions eliminates triphenylphosphine oxide to form an alkene. 

An aldehyde was mixed with solid supported triphenylphosphine oxide (3 equiv.), alkyl halide (4 equiv.), and potassium carbonate (4 equiv.) in methanol (2 ml). The mixture was heated at 150° for 5 min. The residue was filtered through a short plug of silica gel and washed. The solution was concentrated and purified by reverse-phase high-performance liquid chromatography (RP-HPLC). 

Reactions of the bound alkoxyphosphoniura triflate (formed in an identical manner to that of the unbound analog 3a), with the nucleophiles shown in Table II were followed by ir and the yields determined by gc. Our few preliminary results demonstrate that their alkylating abilities are comparable to that of the unanchored alkoxyphosphoniums. The triphenylphosphine oxide polymer produced can be recycled back to the ditriflate, with triflic anhydride. 

There are several oxidation reactions effected by NO that can be incorporated into the BNO scheme. Mercaptans are oxidized to symmetrical disulfides 22), triphenylphosphine to triphenylphosphine oxide, and phosphites to phosphates (18,22), A kinetic study (18) of the reaction of alkyl phosphites with nitric oxide indicates that the reaction is first-order in phosphite and first-order in nitric oxide. This indicates initial formation of a species, BNO ... 

Triphenylphosphine oxide forms stable 1 1 complexes with alkyl hydroperoxides and a 2 1 crystalline complex with dihydrogen peroxide. Infrared and n.m.r. spectroscopic data is given for each complex formed. ... 

In the Wittig reaction an aldehyde and a phosphonium-ylide are coupled to give a new C=C double bond and triphenylphosphine oxide. Depending on the nature of the phosphonium ylide the Wittig reaction is either Z-selective if a labile ylide is employed or E-selective if a stable ylide is used. A labile phosphonium-ylide PhsP-CH-X possesses a substituent X (e.g. alkyl), which is not able to stabilize the negative charge at the carbon atom, whereas a stable ylide... 

Finally, carboxylate 82 attacks the alkylated triphenylphosphine oxide 80 in a normal Sn2 reaction at carbon with triphenylphosphine oxide (85) as the leaving group. Thus, the desired ester 84 is formed, with inversion of the absolute configuration if a chiral alcohol is employed. 

In the first step, the triphenylphosphine reacts with an alkyl azide to form an iminophosphorane with loss of nitrogen Staudinger reaction). In the second step, the nucleophilic nitrogen of the iminophosphorane attacks the carbonyl group to form a four-membered intermediate (oxazaphosphetane) from which the product Schiff base and the byproduct triphenylphosphine oxide are released. 

CCl4-Ph3P is a straightforward and widely used method for converting alcohols to alkyl chlorides. Workup and purification can be tricky at times because of the by-product, PhjPO. An alternative source of PhsP is a commercially available triphenylphosphine resin. The advantage of the resin is that the by-product, triphenylphosphine oxide, is bound to the resin, and purification is simplified. 

In some instances Downie et al.1 found difficulty in separating the alkyl chloride from triphenylphosphine oxide. In such cases, triphenylphosphine can be replaced by hexamethylphosphorous triamide, [(CH3)2N]3P, which is converted into hexa-methylphosphoric triamide, [(CH3)2N ]3PO. 

Indoxyls are normally prepared from anthranilic acids via alkylation with a haloacetic acid followed by a cyclising condensation with loss of carbon dioxide. " Indoxyl itself is best prepared by Friedel-Crafts type ring closure of iV-phenylglycine activated with triphenylphosphine oxide/triflic anhydride in the presence of triethylamine at room temperature. " ... 

The polymeric reagent has been used in conjunction with carbon tetrachloride to convert acids into acid chlorides and alcohols into alkyl chlorides. Yields are generally satisfactory and the work-up merely involves removal of the polymeric triphenylphosphine oxide by filtration. 

The mode of reaction of alkyl- or arylphosphonic halides with Grignard reagents in ether is most often unpredictable. Bis(p-tolyl)phenyl-phosphine oxide is reported as the major product from phenylphos-phonic dichloride and the required quantity of Grignard reagent (148). Attempted synthesis of diallylphenylphosphine oxide under similar circumstances gave only undistillable black oils and tars (13). Equimolar quantities of reactants furnished diphenylphosphinic acid in good yield plus a small quantity of triphenylphosphine oxide (45). 

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