Polymer assisted synthesis

Under certain condition, however, reactions are still preferably conducted in solution. This is the case e.g., for heterogeneous reactions and for conversions, which deliver complex product mixtures. In the latter case, further conversion of this mixture on the solid support is not desirable. In these instances, the combination of solution chemistry with polymer-assisted conversions can be an advantageous solution. Polymer-assisted synthesis in solution employs the polymer matrix either as a scavenger or for polymeric reagents. In both cases the virtues of solution phase and solid supported chemistry are ideally combined allowing for the preparation of pure products by filtration of the reactive resin. If several reactive polymers are used sequentially, multi-step syntheses can be conducted in a polymer-supported manner in solution as well. As a further advantage, many reactive polymers can be recycled for multiple use. 

A method for microwave-assisted transesterifications has been described by Van-den Eynde and Rutot [73], The authors investigated the microwave-mediated deriva-tization of poly(styrene-co-allyl alcohol) as a key step in the polymer-assisted synthesis of heterocycles. Several /i-ketoesters were employed in this procedure and multigram quantities of products were obtained when neat mixtures of the reagents in open vessels were subjected to microwave irradiation utilizing a domestic micro-wave oven (Scheme 7.65). The successful derivatization of the polymer was confirmed by IR, 1H NMR, and 13C NMR spectroscopic analyses. The soluble supports... 

Vickerstaff E, Warrington BH, Ladlow M, Ley SV (2004) Fully automated polymer-assisted synthesis of 1,5-biaryl pyrazoles. J Comb Chem 6 332-339... 

Vanden Eynde, J.J. and Rutot, D., Microwave-mediated derivatization of poly(styrene-co-allyl alcohol), a key step for the soluble polymer-assisted synthesis of heterocycles, Tetrahedron, 1999, 55,2687-2694. 

Despite the current success and popularity of polymer reagents, the availability of functional resins has been a severe limitation in recent years. For many synthetically important transformations, reliable reagents were not available. Moreover, polymer-assisted synthesis was usually restricted to small scale apphcations, and also suffered from the inherent limitations of the standard support material (e.g., cross-linked polystyrene) such as solvent incompatibihty, adsorption of reagents,14 or the chemical reactivity of the resin backbone. 

The first installment in this series (Volume 267, 1996) mostly covered peptide and peptidomimetic based research with just a few examples of small molecule libraries. In this volume we have compiled cutting-edge research in combinatorial chemistry, including divergent areas such as novel analytical techniques, microwave-assisted synthesis, novel linkers, and synthetic approaches in both solid-phase and polymer-assisted synthesis of peptides, small molecules, and heterocyclic systems, as well as the application of these technologies to optimize molecular properties of scientific and commercial interest. 

Ketenes in polymer-assisted synthesis, mainly of heterocycles 03AG(E)2340. 

A fully automated polymer-assisted synthesis of 1,5-biaryl pyrazoles has been reported <04JCO332>. 1,3-Dipolar cycloaddition of resin-supported acrylic acid 53 with phenylhydrazones under microwave irradiation gave resin-bound adducts 54, which were converted to l-phenyl-3-substituted-2-pyrazolinyl-5-carboxylates 55 <04SC3521>. 

Scheme 18. Polymer assisted synthesis of noncentrosymmetrically substituted phthalocyanines (P represents the polymer backbone)...

In this contribution, sulfided Rh catalysts supported on CNTs were prepared by different methods including deposition-precipitation (DP), grafting, and polymer-assisted synthesis. The aim is to improve the dispersion of the aetive phase on CNTs, and enhance the catalytie aetivity and stability of the eatalysts under highly corrosive conditions. 

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