The Lab Notes

The resurgence of peptide and protein-based therapeutics and the demand for chemical probes to elucidate complex biological pathways has driven the development of synthetic chemistry compatible with post translational modification and/or bioconjugation. The use of fluorine-modified biomolecules has enabled the 19F nucleus to be used in NMR experiments to study protein structure, dynamics and protein-ligand…

Esomeprazole is a proton pump inhibitor developed by Astra Zeneca in 2001 and marked under the trade name Nexium. Esomeprazole is the S-enantiomer of omeprazole (the racemate) and is an example of the controversial so-called “chiral switch” in with single isomers are developed and marked as having improved pharmacodynamic or phmacokinetic properties over the originally…

Medicinal chemists love introducing aromatic rings into their pharmacophores. These flat rings make important lipophilic and pi-stacking interactions with proteins and are good synthetic handles for attaching functionality to reach and bind to all the nooks and crannies of an active site. With the advent of cross-coupling chemistry and the simplicity and efficiency of transition…

In December 2017 the United Nations proclaimed that 2019 will be international year of the Periodic Table of the Chemical Elements.[1] This coincides with the 150th anniversary of the periodic system discovered by Dmitry Mendeleev in 1869. We at Scientific Update love a good celebration so over the coming months, and in honour of this…

The direct halogenation of phenols using electrophilic halogenating reagents such as NBS are frequently used to prepare halogenated phenols. The problem with this method is that selectivity can often be low- the ortho- isomer is usually the minor component in a statistical mixture due to steric and electronic effects, and over reaction to give polyhalogenated…

A new paradigm in drug development began in the spring of last year with the Food and Drug Administration’s (FDA’s) approval of Teva pharmaceuticals’ VMAT2 inhibitor deutetrabenazine as a new chemical entity (NCE) under its 501(b)(2) legislation. This molecule is unique in that it is the first deuterium-substituted drug to reach the market and heralds…

The generation of lithium-alkoxide based aryl and heteroaryl Grignard reagents by Mg-Br/Cl exchange in toluene- increased reactivity and wide applicability. Organomagnesium-based organometallics are used extensively in organic chemistry.[1] Historically the reagents were prepared by direct insertion of magnesium metal into organic halides. With demand for more industrially applicable methods, halogen-magnesium exchange using alkyl magnesium halides…

A highly diastereoselective chloride-ion driven dynamic kinetic resolution of a phosphinate ester- a key step in the synthesis of Fosdevirine Fosdevirine (or GSK2248761A, top figure) is a non-nucleoside reverse transcriptase inhibitor, originally discovered by Idenix pharmaceuticals for the treatment of HIV infection. The structure is somewhat unusual in that it contains a phosphorus stereogenic centre-…

One might think that this hard-hitting, students best friend (it will reduce just about anything given the right conditions and is the go-to reducing agent for exam questions involving a reduction) has little more to offer to the practising chemist. However, a recent paper by Harder etal (Angew Chem Int Ed. 2018, 57(24), 7156) demonstrates…

  A patent issued this month cites the use of catalytic tetrabutylammonium bromide (TBAB) in the ring opening esterification of glycidyl ethers using acrylic acid and methacrylic acid (see Example 7). In PTC esterifications, we typically expect the presence of a base to form the carboxylate salt from the acid then the quat acrylate would…