10.1016/j.tetlet.2008.01.026
The study presents the development of a polystyrene-immobilized pyrrolidine (compound 4) as an efficient, reusable, and stereoselective organocatalyst for the asymmetric Michael addition of cyclohexanone to nitroolefins. The catalyst, when combined with trifluoroacetic acid (TFA), enabled the reaction to proceed with high yields (up to >99%) and excellent diastereoselectivities (up to >99:1 dr) and enantioselectivities (up to >99% ee). The purpose of the chemicals used was to facilitate a carbon-carbon bond-formation reaction, which is a crucial process in organic synthesis. The study highlights the environmental friendliness and efficiency of the organocatalyst, as it can be recovered and recycled through simple filtration for more than 10 consecutive trials without significant loss of catalytic activity.
10.1055/s-0030-1258365
The study presents the development and application of a polystyrene-supported zinc bromide-ethylenediamine complex as a reusable and highly efficient heterogeneous catalyst for the synthesis of α,β-acetylenic ketones. This catalyst enables the rapid and efficient synthesis of these ketones through the cross-coupling of acid chlorides with terminal alkynes, yielding good-to-excellent results. The chemicals used in the study include chloromethylated polystyrene, ethylenediamine, zinc(II) bromide, various acid chlorides, and terminal alkynes. The purpose of these chemicals is to create a catalyst that can be easily prepared, is stable, reusable, and efficient under the reaction conditions, and to synthesize α,β-acetylenic ketones, which are important intermediates in organic synthesis with applications as three-carbon building blocks for the synthesis of heterocycles. The study highlights the advantages of using heterogeneous catalysts in coupling reactions, such as waste reduction and ease of catalyst recovery and reuse, contributing to a simpler and more eco-friendly experimental procedure.
10.1248/cpb.33.1849
The research aimed to synthesize a 46-mer DNA duplex containing the promoter of the galactose operon of Escherichia coli, which is significant for understanding gene expression mechanisms, particularly the interactions between regulatory proteins and DNA. The study utilized the solid-phase phosphotriester method, involving the condensation of tetramer or pentamer blocks, to elongate each chain, starting from polystyrene-linked N-protected 3'-sucinyldeoxynucleoside. Key chemicals used in the process included deoxynucleosides, phosphotriester reagents, 1-(mesitylenesulfonyl)-3-nitrotriazole (MSNT) as an activating reagent, and various solvents and reagents for purification steps such as reversed-phase chromatography and ion-exchange chromatography. The conclusion of the research was that by using tetra- or pentanucleotide blocks, deoxypolynucleotides with a chain length of 46 could be synthesized effectively, suggesting that larger oligonucleotide blocks are useful for synthesizing polynucleotides longer than 20, as they simplify isolation procedures and yield purer products. The study also indicated the necessity of preparing larger DNA duplexes for specific interactions with RNA polymerase during transcription.
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