Triphenylphosphine polymer-based

Reactions with polymer-based triphenylphosphine/carbon tetrachloride Nitriles from carboxylic acid amides CONHg CN... 

In this context, it was shown that polymer-supported triphenylphosphine as a ligand for metal-based oxidation is an alternative catalytic system [72]. 

Starting from a hyperbranched polyester based on 4,4 -bis(hydroxyphenyl)valeric acid, terminal -OH groups were derivatized to yield the hyperbranched macroinitiator. The Hgand precursor was introduced as the first block in the grafting from reaction, followed by 2-methyl-2-oxazoHne polymerization to give the second block and allow for water-soluble polymers. The triphenylphosphine-functionalized am-phiphihc star block copolymer was obtained after transformation of the iodoaryl... 

A typical example is the conversion of octanol to actyl chloride in the presence of a carbon tetrachloride-triphenylphosphine reagent. A large increase in rate is measured when polymeric triphenylphosphines replace the momomeric reagent. The effect is particularly noticeable when a cross-linked rather than a linear polymer is used (rate increases 25-fold)157. This phenomenon is attributed to the specific microenvironment of the poly-styrene-divinylbenzene based polymer. Polvmeric phosphines are also used in the conversion of carboxylic acids to acid halides158-165. 

Polymer-supported triphenylphosphine ditriflate (37) has been prepared by treatment of polymer bound (polystyrene-2% divinylbenzene copolymer resin) triphenylphosphine oxide (36) with triflic anhydride in dichloromethane, the structure being confirmed by gel-phase 31P NMR [54, 55] (Scheme 7.12). This reagent is effective in various dehydration reactions such as ester (from primary and secondary alcohols) and amide formation in the presence of diisopropylethylamine as base, the polymer-supported triphenylphosphine oxide being recovered after the coupling reaction and reused. Interestingly, with amide formation, the reactive acyloxyphosphonium salt was preformed by addition of the carboxylic acid to 37 prior to addition of the corresponding amine. This order of addition ensured that the amine did not react competitively with 37 to form the unreactive polymer-sup-ported aminophosphonium triflate. 

Reactions of fp-Polvstvrylmethvlltriphenvlphosphonium Ions. In these reactions the polymer-bound phosphorane reacts with an aldehyde or ketone to produce an alkene substituent on the polymer and leave the by-product triphenylphosphine oxide in solution, where it can be washed away from the polymer. The results are in Table II. Many of the same methods of phosphorane generation used to produce soluble alkenes were used. The yields in Table II are less accurate than the yields of micromolecular alkenes in Table 1 because of the difficulty of analysis of insoluble polymers. The yields have been based on weight changes of the polymer, analysis of the polymer for an element introduced during the reaction, the yield of triphenylphosphine oxide, or the amount of bromine consumed by the modified polymer. 

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