Polymer-bound sodium

Alternatively polymer-bound sodium selenide 6 served as the starting point for an acylat-ing protocol (Scheme 3) [12]. Transformation into selenol ester 9 afforded an active polymer-bound intermediate which was cleaved in the presence of an alkinylcopper species to generate a,/ -alkinyl ketones 10 while the copper selenide can be reacylated using acyl chlorides. 

Pyrazoline, Isoxazoline, andBenzofb][1,4Jdiazepine Derivatives. The sulfone linker 44 derived Irom 43 is a versatile and robust tether and many new applications of this linker have been explored. To demonstrate the use of 44 as a versatile and robust tether that offers various on-resin functionalization or cleavage with additional changes, Lam and coworkers have highlighted the preparation of the five-membered pyrazoUne/isoxazoline 48 as well as the fused benzodiazepine 47 (Scheme 12.11). The polymer-bound sodium sulfinate resin 43 was treated with benzyl bromide using NBU4I/KI/DMF to yield 5-alkylated sulfone... 

An analytical solution for molecules with alkaline functionality is acid/base titration. In this technique, the polymer is dissolved, but not precipitated prior to analysis. In this way, the additive, even if polymer-bound, is still in solution and titratable. This principle has also been applied for the determination of 0.01 % stearic acid and sodium stearate in SBR solutions. The polymer was diluted with toluene/absolute ethanol mixed solvent and stearic acid was determined by titration with 0.1 M ethanolic NaOH solution to the m-cresol purple endpoint similarly, sodium stearate was titrated with 0.05 M ethanolic HC1 solution [83]. Also long-chain acid lubricants (e.g. stearic acid) in acrylic polyesters were quantitatively determined by titration of the extract. 

Devaky and Rajasree have reported the production of a polymer-bound ethylenediamine-borane reagent (63) (Fig. 41) for use as a reducing agent for the reduction of aldehydes.87 The polymeric reagent was derived from a Merrifield resin and a 1,6-hexanediol diacrylate-cross-linked polystyrene resin (HDODA-PS). The borane reagent was incorporated in the polymer support by complexation with sodium borohydride. When this reducing agent was used in the competitive reduction of a 1 1 molar mixture of benzaldehyde and acetophenone, benzaldehyde was found to be selectively reduced to benzyl alcohol. 

The simplest C-C bond formation reaction is the nucleophilic displacement of a halide ion from a haloalkane by the cyanide ion. This was one of the first reactions for which the kinetics under phase-transfer catalysed conditions was investigated and patented [l-3] and is widely used [e.g. 4-12], The reaction has been the subject of a large number of patents and it is frequently used as a standard reaction for the assessment of the effectiveness of the catalyst. Although the majority of reactions are conducted under liquiddiquid two-phase conditions, it has also been conducted under solidrliquid two-phase conditions [13] but, as with many other reactions carried out under such conditions, a trace of water is necessary for optimum success. Triphase catalysis [14] and use of the preformed quaternary ammonium cyanide [e.g. 15] have also been applied to the conversion of haloalkanes into the corresponding nitriles. Polymer-bound chloroalkanes react with sodium cyanide and cyanoalkanes under phase-transfer catalytic conditions [16],... 

A number of modified reaction conditions have been developed. One involves addition of silver salts, which activate the halide toward displacement.94 Use of sodium bicarbonate or sodium carbonate in the presence of a phase-transfer catalyst permits especially mild conditions to be used for many systems.95 Tetraalkylammonium salts often accelerate reaction.96 Solid-phase catalysts in which the palladium is complexed by polymer-bound phosphine groups have also been developed.97 Aryl chlorides are not very reactive under normal Heck reaction conditions, but reaction can be achieved by inclusion of triphenylphosphonium salts with Pd(OAc)2 or PdCl2 as the catalyst.98... 

Reaction of Resin-Bound Iron Complex (54) with Alkyl Mercaptans, Thiophenols, and Phenols (Fig. 9)31. Sodium thiolates are prepared analogously to the alkoxides from thiol and sodium hydride, except that dry DMF is used as a solvent. The substitution on the polymer-bound arene (54) is performed at 70° in DMF within 16 h. The resin is filtered and washed with DMF (2 x 50 ml), MeOH (2 x 50 ml), H20 (2 x 50 ml), MeOH (2 x 50 ml), and CH2CI2 (3 x 50 ml) and then dried in vacuo at 40° to yield a red resin. 

Influence of polymerization conditions upon incorporation of flavin-containing polyanion. The amount of polyanion (1) incorporated as dopant in a PPy film during electropolymerization can easily be controlled by changing the ionic strength (low molar mass salt) and/or the pH of the monomer solution. The correlation between the amount of polymer-bound flavin incorporated in the film and the concentration of the added low molar mass salt, sodium-p-toluenesulphonate (NaOTs), at pH=7 is shown... 

Exchange of potassium or sodium iodide with primary alkyl bromides or chlorides is one of the most thoroughly studied phase transfer reactions173,174. It is normally performed in a two-phase aqueous/organic system utilizing a soluble or a polymer-bound PTC. Starks and collaborators have shown175,176 that primary alkyl chlorides or bromides quantitatively exchange with aqueous sodium iodide in the presence of few mol% of a soluble quaternary ammonium PTC at 108 °C within a few hours (secondary alkyl halides normally yield elimination products under these conditions). The mechanism, which is typical of PTC, comprised two consecutive steps ... 

The alternative reverse addition procedure can give incomplete reduction of the alkyne (33). An increase in the ratio of liquid ammonia to alkyne (34), the addition of co-solvents (23), the use of lithium rather than sodium, or the use of a higher temperature in an autoclave are advisable for the reduction of high molecular weight alkynes to overcome solubility problems which can also result in incomplete reduction. The resulting olefin is usually very pure ji isomer containing no detectable Z isomer. Use of an alcohol as a co-solvent and proton donor can accelerate the reduction, but the resulting olefin then contains a minor amount of the Z isomer. Polymer-bound alkynes can not be successfully reduced with sodium in liquid ammonia (35). 

The preparation of polymer bound Ni-chelates (54) of the acac type started from chloromethylated polystyrene and pentane-2,4-dione leading with catalytic amounts of sodium ethoxide to the polymer diketone (53) (Eq. 21) Seven % of pendent diketone groups of soluble linear (55) were converted with 1,2-diamtnoethane and Ni(II) to the polymer Sdiifr base chelate (54). In the reaction of (55) to (54) two pendent diketon must react. But surprisingly no network formation was reported. 

Alternative Fmoc donors have been proposed for particular purposes for example, [4-(9-fluorenylmethoxycarbonyloxy)phenyl]dimethylsulfonium methylsulfate (20) has been proposed by Okai et al. as a water-soluble reagent for the introduction of the Fmoc group in the presence of aqueous sodium carbonate. O Similarly, a polymer-bound 1,2,3-benzo-triazol-l-ol can be converted by reaction with 9-fluorenylmethyl chloroformate (17) into a polymer-bound 1,2,3-benzotriazol-l-yl 9-fluorenyhnethyl carbonate for the preparation of Fmoc-protected amines in organic and aqueous organic media with all the known advantages of insoluble reagents. ... 

The reaction of an aldehyde with sodium azide and Et4 l(OAc)2 or polymer-bound Phl(OAc)2 leads to an acyl azide. 

A convenient one-step transformation of primary and secondary amines into the corresponding unprotected guanidines using 4-benzyl-3,5-dimethyl-l/f-pyrazole-l-carboxamidine 90 and its polymer-bound variant were described <06S461>. 1,3-Dipolar cycloaddition of polymer-bound alkynes to azomethine imines generated in situ from N-aminopyridine iodides followed by aromatization of the cycloadducts gave polymer-bound pyrazolopyridines that were released from the resin as carboxylic acids with trifluoroacetic acid or as methyl esters with sodium methoxide <06JCO344>. 

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