Polymer-supported reagents groups

We would like to acknowledge the contributions and commitment of all the members of the Polymer-Supported Reagents Group at the University of Cambridge and to thank Pfizer (Sandwich) Postdoctoral Fellowship (to IRB), the BP endowment, Cambridge Discovery Chemistry and the Novartis Research Fellowship (to SVL) for their financial support. 

One widely used method of formation of protected compounds involves polymer-supported reagents, with the advantage of simple workup by filtration and automated syntheses, especially of polypeptides. Polymer-supported reagents are used to protect a terminal — COOH group as a polymer-bound ester (RCOOR —( ) during peptide syntheses, to protect primary alcohols as... 

Polymer supported reagents, catalysts, protecting groups, and mediators can be used in place of the corresponding small molecule materials (Sherrington, 1991 Sundell and Nasman, 1993). The reactive species is tightly bound to a macromolecular support which immobilizes it. This generally makes toxic, noxious, or corrosive materials much safer. The use of polystyrene sulfonic acid catalyst for the manufacture of methyl r-butyl... 

From a medicinal chemist s point of view, oxadiazoles are among the most important heterocycles as they are one of the most commonly used bioisosters for amide and ester groups [67]. As such it is hardly surprising that the two regioisomeric oxadiazole scaffolds received the most interest in the field of microwave-assisted synthesis using polymer-supported reagents. 

Two polymer-supported reagents have been developed for the oxidation of sulphoxides to sulphones these involve peracid groups , and bound hypervalent metals activated by t-butyl hydroperoxide . ... 

One research group has exploited the concept of polymer site-isolation in a multistep/one-chamber solution-phase synthesis in which all the reagents, catalysts, and downstream reactants required for a multistep synthesis were combined in one reaction chamber. For instance, a one-chamber/three-step synthesis of substituted acetophenones has been reported (Scheme 10).84 An a-phenethyl alcohol was introduced into a reaction chamber containing the polymer-supported reagents and reactants necessary to accomplish oxidation by polymer-supported pyridinium dichromate 60 bromination by the A-26 perbromide resin 61 and nucleophilic displacement by the A-26 phenoxide resin 62. Filtration afforded the... 

When a sample containing a polymer-supported reagent is subjected to electromagnetic irradiation, it is possible for the energy to be directly coupled to polar functional groups. It then takes a defined period of time for the absorbed energy to dissipate... 

Recognition of these drawbacks prompted the Ley group to design a new polymer-supported reagent 9 for direct amide thionation149. Preparation of this immobilised... 

Rao, N.S., Agarwal, S.K., Chauhan, V.K., Bhatia, D., Sharma, A.K. et at, Microwave-assisted spectropho-tometric estimation of polymer-supported functional groups using a universal reagent, Anal. Chim. Acta, 2000, 405, 247. 

Allyltributyltin can be used in combinatorial radical allylation. Moreover, a polymer-supported reagent bearing an allyltin group was also developed and it can be used for the radical allylation of alkyl halides. 

Organic hydroperoxides are generally used for the preparation of sulfoxides from sulfides, - while sulfones can be obtained in neutral organic solvents in the presence of metal catalysts such as V, Mo and Ti oxides at 50-70 C. Two polymer-supported reagents which involve peroxy acid groups and bound hypervalent vanadium(V) and molybdenum(VI) compounds have been developed for facile oxidation of sulfoxides to sulfones. 

However, early attempts at synthesising compound arrays using polymer-supported reagents and automation proved to be problematic. Our group used an ACT 496 automated synthesiser to produce a 96-membered array of compounds in a single automated step. In this array, 12 aromatic aldehydes were reacted with eight aliphatic amines in the presence of polymer-supported cyanoborohydride to produce the corresponding secondary amines 33 (Scheme 11). 

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