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In this review, the concept and various strategies in molecular imprinting is discussed briefly. How the concept of transition state analogue can be used to design a template to prepare catalytic imprinted polymers is described in detail. The use of the "bait and switch" approach and alternative covalent template strategies show how functional groups which assist in the catalytic properties can be assembled within the imprint. Thus, there are so many reports on P catalyzed reactions. Owing to their advantageous properties over natural biological recognition agents, molecularly imprinted polymers (MIPs) therefore offer great potential for various applications.

This Review describes the existing synthetic approaches for the solid-phase synthesis (SPS) of differently substituted and fused pyrimidine derivatives. These synthetic strategies are classified on the basis of the different synthetic routes leading to the particular type of pyrimidine heterocycle formed. The Review discusses the application of a variety of polystyrene derived supports for the construction of pyrimidine rings. The effect of microwave heating on the solid-phase synthesis is also addressed in the review.

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ABSTRACT:A polymer-supported ethylenediamine (EDA)-borane reagent was prepared under mild reaction conditions. The reagent was found to be efficient and selective in the reduction of aldehydes to the corresponding alcohols in high yields at room temperature. The polymeric reagent was prepared on a Merrifield resin and on a 1,6-hexanediol diacrylate-crosslinked polystyrene resin (HDODA-PS). HDODA-PS was prepared by suspension polymerization and chloromethylated by a Friedel-Crafts reaction. The preparation of the polymer-bound EDA-borane reagent involves a series of polymer analogous reactions, such as amination of the chloromethyl resin, conversion to amine hydrochloride, and, finally, complexation with sodium borohydride. The reagent exhibited good chemoselectivity in the reduction of aldehydes. The reduction reactions were carried out with a 2 molar excess of the polymeric reagent. In the competitive reduction of a 1:1 molar mixture of benzaldehyde and acetophenone, benzaldehyde was selectively reduced to benzyl alcohol. The spent resin could be recycled by treating with sodium borohydride. The recycled resin was used several times without much loss in chemical reactivity and mechanical stability. The HDODA-PS resin was found to be more efficient than was the Merrifield resin in the preparation of the reagent as well as in the reduction reactions.

This article illustrates the successful and efficient solid phase assembly of hydrophobic difficult sequence peptides following both t-Boc and Fmoc chemistry. The peptides were synthesized on an optimized 1,4-butanediol dimethacrylate-crosslinked polystyrene support (BDDMA-PS). Four difficult sequence test peptides, VAVAG, VIVIG, QVGQVELG and VQAAIDYING, were synthesized in relatively good yield and purity without any aggregation problems. The peptides were assembled on chloromethylated and 4-hydroxymethylphenoxymethyl (HMP) BDDMA-PS resins. The peptides were fabricated using Boc amino acid 1-hydroxybenzotriazolyl and Fmoc amino acid pentafluorophenyl active esters in coupling reactions. The peptides after synthesis were cleaved from the polymeric support by exposing the peptidyl resin to 90% trifluroacetic acid/5% thioanisole/5% EDT mixture. The HPLC and MALDI TOF MS studies of the peptides revealed the high homogeneity of the synthesized peptides. Chloromethylated resin having a functional group loading of 1.14 mmol Cl/g was used for the synthesis. The yield and homogeneity of these peptides synthesized using the new support were high when compared with the conventional DVB-PS resin.

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