Changing Requirements of Purification as Drug Discovery Programs Evolve from Hit Discovery

The Chosen Few: Parallel Library Reaction Methodologies for Drug Discovery

Parallel library synthesis is an important tool for drug discovery because it enables the synthesis of closely related analogues in parallel via robust and general synthetic transformations. In this perspective, we analyzed the synthetic methodologies used in >5000 parallel libraries representing 15 prevalent synthetic transformations. The library data set contains complex substrates and diverse arrays of building blocks used over the last 14 years at AbbVie. The library synthetic methodologies that have demonstrated robustness and generality with proven success are described along with their substrate scopes. The evolution of the synthetic methodologies for library synthesis over the past decade is discussed. We also highlight that the combination of parallel library synthesis with high-throughput experimentation will continue to facilitate the discovery of library-amenable synthetic methodologies in drug discovery.

Expanding Synthesizable Space of Disubstituted 1,2,4-Oxadiazoles

One-pot synthesis of 3,5-disubstituted 1,2,4-oxadiazoles from carboxylic acids and nitriles was optimized to parallel chemistry. The method was validated on a 141 member library; the desired products were recovered with a high success rate and in moderate yields. Practical application of the approach was demonstrated in the synthesis of bioactive compound pifexole and agonists of free fatty acid receptor 1. A library of 4 948 100 synthesizable drug-like 3,5-disubstituted 1,2,4-oxadiazoles was enumerated based on the method and available validated reagents.

Advances in improving the quality and flexibility of compound management

The process of drug discovery has evolved considerably since the advent of high-throughput screening (HTS) in the 1980s. Experts and opinion leaders today are agreeing that the current trend in the field is a focus on increasing overall quality (target, screening, and compounds), use of multiple screening approaches for lead discovery, and more flexibility in the process. The associated need for increased flexibility and quality control to support existing HTS paradigms as well as lower throughput approaches such as fragment screening, computational chemistry, focused library building, and centralized lead optimization support has required an evolution in compound management (CM, aka sample management or library management). Although there is much less published peer-reviewed data in CM, due to its historical links to HTS, it has followed very similar trends. In recent years, the focus in CM has been increasingly in compound quality and increased flexibility of the process, as opposed to number of compounds dispensed and speed of dispensing, which were standard metrics and indicators used not so long ago. Ideally, to screen the highest quality sample for every assay, one would start with a correct identity and pure solid, make a correct concentration solution in water or water-soluble/assay-compatible solvent that would allow 100% solubilization, and screen it immediately in a biological assay. Neither CM nor screening has advanced sufficiently to deliver this ideal scenario, but many significant advancements have been made in recent years both in terms of quality of compounds in stores and flexibility of the process, which will be reviewed herein.

Drug discovery chemistry: a primer for the non-specialist

Like all scientific disciplines, drug discovery chemistry is rife with terminology and methodology that can seem intractable to those outside the sphere of synthetic chemistry. Derived from a successful in-house workshop, this Foundation Review aims to demystify some of this inherent terminology, providing the non-specialist with a general insight into the nomenclature, terminology and workflow of medicinal chemists within the pharmaceutical industry.

Informatics in compound library management

The ability to accurately and efficiently manage inventory is critical to ensure cost-effectiveness and guarantee integrity of samples in drug discovery. While many large companies utilise both customised and off-the-shelf automated systems for compound library management, these systems do not come cheaply. Without doubt, for large pharma the return on investment for one of these systems can be justified; however, the upfront cost is typically prohibitive for smaller businesses looking to stretch their limited cash reserves as far as possible. At Exelgen we have shown that for any business with the combination of fit-for-purpose informatics, relatively inexpensive laboratory hardware and well-constructed SOPs (standard operating procedures), it is possible to undertake cost-effective, large-scale compound library management in a small business environment. The informatics and hardware environment deployed at Exelgen are described in detail.