Case Studies

Summary: Removing protecting groups from a synthesis pathway can prove difficult. In order to overcome this challenge, a method using SiliaMetS Thiol was developed for the deprotection of various aromatic and aliphatic acetals to their corresponding catechol or diol derivatives.

Summary: Azide-alkyne cycloadditions are pioneering reactions to click chemistry as they fulfill many of the prerequisites & principles this new chemical philosophy is aiming for. More specifically, copper-catalyzed azide–alkyne cycloadditions (CuAAC) are important reactions for the generation of bioactive molecules. However, as we know copper salts are toxic toward living systems and have deleterious effects on redox-sensitive nanoparticles which is why their removal after conjugation is important. In this case study a more elegant strategy is herein described eliminating the need for EDTA or dialysis often found in the clasical protocols. Following a terminal alkyne-selective click conjugation with azides, Prof. Hosoya and co-workers screened various metal scavengers in order to select the most potent chelator in the removal of copper. SiliaMetS Thiourea was shown to be the most valuable, among other SiliCycle Metal Scavengers and a PS-TPP resin.

Summary: The efficiency of the Buchwald-Hartwig catalyst to achieve C-N bond formation makes it very frequently used in organic synthesis, however its high cost and limited supply is less attractive for multigram-scale C−N bond formation. In this article, researchers explored using the catalyst for the C-N cross-coupling of aryl amines with aryl halides in a biphasic aqueous solution. This approach allowed for an efficient synthesis with high yields to be achieved for kilogram-scale reactions.

Summary: The copper-catalyzed azide-alkyne cycloaddition (CuAA), or also known as «click chemistry», has been widely used to functionalize molecules with various moieties. In their previous work, Prof. Hosoya and co-workers presented a new strategy to synthetize cycloalkynes incorporating various functional moities by protecting the diynes with a copper salt. At the time, SiliaMetS Thiourea was shown to be the most efficient scavenger to remove copper from the click reaction mixture.

Summary: The authors of the study performed a regioselective tin-mediated alkylation to access the N-1 alkylated tetrazole isomer. A highly selective enzymatic hydrolysis provided the desired prodrug enantiomer. For the final fragment union, a Suzuki–Miyaura coupling was employed, leading to the need to eliminate both tin and residual palladium catalyst from the API in multikilogram quantities.

Summary: The bromo- and extra-terminal domain (BET) family of proteins is known to play a major role in the regulation of gene transcription. An intense area of research is now using BET inhibitors for possible cancer treatment, and their therapeutic effects are being investigated. GSK973 is one such inhibitor, needed in larger quantities for pre-clinical efficacy and safety studies for oncology trials. By working on improving the synthetic route for its large-scale synthesis, the team at GSK included a purification step using SiliaMetS Thiol for the removal of the residual Pd catalyst.

Summary: Electronic waste (e-waste) is the collection of used devices including cell phones, TVs, monitors, tablets and other unwanted consumer gadgets often destined for landfill. These devices tend to contain many precious metals (copper, gold, silver, palladium...) especially within the circuit boards found within. There is a growing demand for proper disposal in order to extract these metals for reuse and reduce mining operations. This Case Study details the extraction of palladium and silver from circuit boards using SiliaMetS Thiol prior to a subsequent recycling step.

Summary: For uncomplicated malaria, Artemisinin is currently the first-line treatment. Unfortunately, the emergence of Artemisinin resistance calls for the development of alternative antimalarial treatments. The Novartis Institute for Tropical Diseases screened compounds to identify fast-acting molecules with a new chemotype...

Summary: Silver ions in environmental water can hinder analytic measurements of the water’s nanoparticle content. Different solid phase extraction (SPE) materials were investigated to remove the silver ions without disturbing the silver nanoparticles in the samples. Among the products tested, SiliCycle’s SiliaMetS Metal Scavengers were promising candidates for the preparation of water samples for nanoparticle analysis.

Summary: Enzyme-loaded hydrogels have potential uses as catalytic reactors to convert prodrugs into anti-cancer drugs in vivo. The hydrogels are formed by amphiphilic glycopeptides synthesized by copper catalyzed Huisgen reactions. Residual copper is scavenged using SiliaMetS Triamine.