Triphenylphosphite

Iodoallenes can also be prepared in reasonable yields by treatment of secondary acetylenic alcohols with triphenylphosphite-methyl iodide, using DMF as a solvent. One of the -OPh groups is probably first replaced by the propargyloxy group. This intermediate subsequently undergoes attack by iodide on the terminal acetylenic carbon atom, affording the iodoallene in a 1,3-substitution ... 

Conventional triorganophosphite ligands, such as triphenylphosphite, form highly active hydroformylation catalysts (95—99) however, they suffer from poor durabiUty because of decomposition. Diorganophosphite-modified rhodium catalysts (94,100,101), have overcome this stabiUty deficiency and provide a low pressure, rhodium catalyzed process for the hydroformylation of low reactivity olefins, thus making lower cost amyl alcohols from butenes readily accessible. The new diorganophosphite-modified rhodium catalysts increase hydroformylation rates by more than 100 times and provide selectivities not available with standard phosphine catalysts. For example, hydroformylation of 2-butene with l,l -biphenyl-2,2 -diyl... 

Rydon and co-workers (73) have shown that the reaction of simple alcohols with triphenylphosphite methiodide and triphenylphosphite dihalides gives alkyl halides according to the general scheme. 

In addition to simple halides, the method was used to prepare chol-esteryl iodide (30%) and cyclohexyl iodide (34%) from the corresponding alcohols, thus demonstrating the applicability of the reaction to cyclic secondary alcohols. An early adaptation to carbohydrates was reported by Lee and El Sawi (75). They claimed that treatment of l,2 5,6-di-0-isopropylidene-D-glucofuranose (49) with triphenylphosphite methiodide... 

The reaction is quite susceptible to steric effects since hindered secondary hydroxyl groups were found to be unreactive. The method can therefore be used to selectively replace a primary hydroxyl group by halogen in the presence of more hindered secondary hydroxyl groups in the same molecule. An example (70) is the reaction of 52 with triphenylphosphite methiodide which affords the 6-deoxy-6-iodo derivative 53 (60%) in which the C-2 hydroxyl group remains intact. 

Whereas l,2-0-isopropylidene-5,6-di-0-methyl-D-glucofuranose was found to be unreactive towards triphenylphosphite dibromide, triphenylphosphite methiodide or phosphorus pentachloride, the related methyl 2,5,6-tri-0-methyl-/ -D-glucofuranoside (59), in which the hindrance caused by the ketal group is absent, reacted with triphenylphosphite methiodide to give the 3-deoxy-3-iodo derivative 60 in 31% yield. 

In a similar way, 5-O-acetylthymidine was converted into the 3-deoxy-3-iodo derivative 72 in 55% yield. In this case, the replacement of the hydroxyl group by iodine was presumed to have taken place by retention of the configuration at C-3. The first intermediate in the reaction was proposed to be the phosphonate (70) which rapidly collapses to an O-3-cyclonucleoside (71) and the latter is subsequently attacked by iodide ion to give the product 72. It was also observed (106) that treatment of nucleosides containing a cis vicinal diol grouping such as 5-0-acetyluridine with triphenylphosphite methiodide failed to provide iodinated products but gave phosphonate derivatives instead. 

Tractable polymers can be prepared when amino and anhydride functions are not located on the same aromatic ring, and different strategies were employed to obtain soluble polymer. AB benzhydrol imide was prepared by polycondensation of 4-(3-amino-l-hydroxymethylene) phtlialic acid monomethyl ester in NMP. The polymer soluble in NMP has been used as adhesive and coating.56 A second approach was based on an ether imide structure. AB aminophenylether phthalic acids (Fig. 5.34) were prepared by a multistep synthesis from bisphenols.155 The products are stable as hydrochloride, and the polycondensation takes place by activation with triphenylphosphite. The polymers are soluble in an aprotic polar... 

Some of the important results for butadiene are summarized in Table XV. The most efficient system identified was for cis-polymerization using 1 1 molar ratio of (XXI) with trifluoroacetic acid. An even more remarkable observation, however, was the almost complete suppression of the cis-polymerization in favor of trans-polymerization processes on addition of triphenylphosphite to the mixture of (XXI) and trifluoroacetic acid. More recently (89), Durand and Dawans have synthesized the trifluoroacetates (XXIII) where R = H and C9H15, and these were shown to be catalytically active as well as exhibiting some specificity in polymerization of butadiene and isoprene. 

The titanocene monocarbonyl-triphenylphosphite complex, Cp2Ti-(CO)[P(OPh)3] (46) has also been prepared by this method (50). The cyclopentadienyl protons of 46 appeared as a doublet (/h p = 2.5 Hz) 46, while the parent ion (m/e = 516) was found in the mass spectrum. 

A base-mediated type lb cyclocondensation of imino chlorides, derived from treating the corresponding A-allylamides with triphenylphosphite-chloride, provided 2-aryl- and 2,3-diarylpyrroles <06S995>. 

More than half of the members of this family have been structurally characterized and the Au-C distances correlated with the donor ability of the /rchemical shifts of 13C resonances in the NMR spectra. According to these results, the /rcarbene ligand appears to be comparable to that of triphenylphosphite P(OPh)3. Owing to the bulkiness of the lBu substituents, the complexes are not aggregated in the crystals. By contrast, the corresponding methyl-substituted compounds are aggregated to form chains via aurophilic contacts and are photoluminescent.18... 

Very subtle ligand effects have been detected in these reactions. Thus, under the same conditions, 1 mole of tricyclohexylphosphine and 1 mole of Ni(COD)2 in the presence of excess morpholine catalyze addition of acetophenone to 2 moles of butadiene to give compound A below, whereas triphenylphosphine gives B. With triphenylphosphite C—C coupling no longer occurs, but morpholine adds to butadiene to give C (135). 

Iodotrimethylsilane formed in situ from the reaction of chlorotrimethylsilane and sodium iodide, also effects the conversion of 2-ene-l,4-diols to 1,3-dienes (equation 16)46. Allylic thionocarbonates on heating with triphenylphosphite undergo deoxygenation (Corey-Winter reaction) to generate olefins47. This procedure has been used for making hexatrienes (equation 17)47b. 

The Osmium cluster Os3(CO)12 and clusters in the presence of various phosphines and triphenylphosphite have been utilized for the hydrogenation of cinnamaldehyde and crotonaldehyde (Table 15.7) [36]. The results show that good yields of unsaturated alcohols can be obtained by using a large excess of phosphine at elevated hydrogenation temperatures. 

The first iridium catalysts for allylic substitution were published in 1997. Takeuchi showed that the combination of [fr(COD)Cl]2 and triphenylphosphite catalyzes the addition of malonate nucleophiles to the substituted terminus of t -allyliridium intermediates that are generated from allylic acetates. This selectivity for attack at the more substituted terminus gives rise to the branched allylic alkylation products (Fig. 4), rather than the linear products that had been formed by palladium-catalyzed allylic substitution reactions at that time [7]. The initial scope of iridium-catalyzed allylic substitution was also restricted to stabilized enolate nucleophiles, but it was quickly expanded to a wide range of other nucleophiles. 

Although most of these early reactions were conducted with allylic acetates, reactions of allylic carbonates, trifluoroacetates, and phosphates also occur. Sodium diethylmalonate also reacts with allylic alcohols in the presence of the iridium-triphenylphosphite catalyst. However, the alcohol itself does not act as a leaving group. Instead, transesterification occurs with one equivalent of malonate nucleophile to form a more labile ester leaving group. 

Addition to linear 1,1-disubstituted allylic acetates is slower than addition to monosubstituted allylic esters. Additions to allylic trifluoroacetates or phosphates are faster than additions to allylic carbonates or acetates, and reactions of branched allylic esters are faster than additions to linear allylic esters. Aryl-, vinyl, alkynyl, and alkyl-substituted allylic esters readily undergo allylic substitution. Amines and stabilized enolates both react with these electrophiles in the presence of the catalyst generated from an iridium precursor and triphenylphosphite. 

There are many phosphine and phosphite complexes of iron(O), sometimes acting as P,C-donors in orthometallated complexes. In general this area is deemed to be organometallic chemistry, so we shall cite just one recent reference to act as a possible point of entry to this area, relating to [Fe(CO)2 P(OPlfi3 P(OPh)2(OC6Fl4) which contains both a P- and a P,C-donor triphenylphosphite ligand. ... 

Diaminopyrimidine is reported to react with triphenylphosphite to give 1,3,2-diazaphos-pholo[l,5-. In both cases, however, the physical properties of the isolated materials are in accord with oligomers rather than with monomeric azaphospholes. 

Benzoyl ester 55a was then hydrolyzed with aqueous sodium bicarbonate to enantio-merically pure alcohol 56 in 91% yield (Scheme 4.6). The alcohol was converted to iodide 57 with triphenylphosphite methyliodide in excellent yield. Iodide 57 was next reduced under radical conditions, and the resulting core was hydrolyzed with hydrochloric acid in acetic acid to furnish carboxylic acid 58 in 44% yield over two steps. Finally, the 7-fluoroquinolone was allowed to react with iV-methylpiperazine in DMSO at 130-140°C to deliver (—)-ofloxacin, levofloxacin (1), in 52% yield. 

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