The Lab Notes

         2-Aminopyrides are useful synthetic intermediates and pharmacophores in a number of drugs.[1] The Chichibabin reaction, developed in the 1900’s gives a direct method for the amination of pyridine and pyridine derivatives (azines and azoles) using sodium or potassium amides. Intramolecular amination reactions are also known. The reaction can be run either…

I always look forward to publication of the annual review synthetic approaches to the new drugs approved for the preceding year. In some ways its bitter sweet since it acts as a reminder of how difficult drug discovery and development is and how the large volume of molecules that start their journey never actually make…

One of the first encounters I had with complex structures and challenging organic synthesis was a course I took on the synthesis of antibiotics as an undergraduate chemist at Bath university almost thirty years ago. These molecules and I had had a love hate relationship for much of my early childhood, having consumed what must…

The Mitsunobu reaction is a powerful coupling method for alkylation of various nucleophiles (H-A) with alcohols (R-OH).[1] The classical conditions use a redox system comprising of an azodicarboxylate (such as diethylaziodicarboxylate, DEAD) and a phosphine (normally triphenylphosphine, TPP). The alcohol is essentially activated in situ and coupling occurs with the generation of the phosphine oxide…

One of the challenges associated with biocatalysis is the resulting stereochemistry is not always easy to predict and more often than not gives the unwanted isomer. The problem is compounded if the substrate has limited steric or electronic components to aid stereocontrol. A way around this problem is to engineer the wildtype protein. A resent…

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…