A Structurally Diverse Library of Polycyclic Lactams Resulting from Systematic Placement of Proximal Functional Groups

Diversity through a branched reaction pathway: generation of multicyclic scaffolds and identification of antimigratory agents

A library of 91 heterocyclic compounds composed of 16 distinct scaffolds has been synthesized through a sequence of phosphine-catalyzed ring-forming reactions, Tebbe reactions, Diels-Alder reactions, and, in some cases, hydrolysis. This effort in diversity-oriented synthesis produced a collection of compounds that exhibited high levels of structural variation both in terms of stereochemistry and the range of scaffolds represented. A simple but powerful sequence of reactions thus led to a high-diversity library of relatively modest size with which to explore biologically relevant regions of chemical space. From this library, several molecules were identified that inhibit the migration and invasion of breast cancer cells and may serve as leads for the development of antimetastatic agents.

Targeting protein–protein interactions for therapeutic intervention: a challenge for the future

Background: Over the last two decades, an increasing research effort in academia and industry has focused on the modulation (both inhibition and stabilization) of protein–protein interactions (PPIs) in order to develop novel therapeutic approaches and target-selective agents in drug discovery. Discussion: The diversity and complexity of highly dynamic systems such as PPIs present many challenges for the identification of drug-like molecules with the ability to modulate the PPI with the necessary selectivity and potency. In this review, a number of these strategies will be presented along with a critical overview of the challenges and potential solutions relating to the exploitation of PPIs as molecular targets. Conclusions: Both traditional drug discovery approaches and some more recently developed innovative strategies have already provided valuable tools for the discovery of PPI modulators, and a number of successful examples have highlighted the potential of targeting PPIs for therapeutic intervention, especially in the oncology area.

Towards the optimal screening collection: a synthesis strategy

The development of effective small-molecule probes and drugs entails at least three stages: 1) a discovery phase, often requiring the synthesis and screening of candidate compounds, 2) an optimization phase, requiring the synthesis and analysis of structural variants, 3) and a manufacturing phase, requiring the efficient, large-scale synthesis of the optimized probe or drug. Specialized project groups tend to undertake the individual activities without prior coordination; for example, contracted (outsourced) chemists may perform the first activity while in-house medicinal and process chemists perform the second and third development stages, respectively. The coordinated planning of these activities in advance of the first small-molecule screen tends not to be undertaken, and each project group can encounter a bottleneck that could, in principle, have been avoided with advance planning. Therefore, a challenge for synthetic chemistry is to develop a new kind of chemistry that yields a screening collection comprising small molecules that increase the probability of success in all three phases. Although this transformative chemistry remains elusive, progress is being made. Herein, we review a newly emerging strategy in diversity-oriented small-molecule synthesis that may have the potential to achieve these challenging goals.

A Substrate-Based Folding Process Incorporating Chemodifferentiating ABB′ Three-Component Reactions of Terminal Alkynoates and 1,2-Dicarbonyl Compounds: A Skeletal-Diversity-Oriented Synthetic Manifold

A novel three-component reaction (3CR)-based folding process that is able to generate complexity and skeletal diversity is described. The process utilizes chemodifferentiating organocatalyzed ABB' 3CRs of a terminal conjugated alkynoate (building block) with alpha-dicarbonyl compounds (diversity-generating blocks) to generate an array of different molecular topologies (gamma-lactones, linear propargylic enol ethers, or 1,3-dioxolane rings). Amides and esters behave as efficient reactivity-encoding elements (sigma) of the attached keto functionality. Three chemical properties govern the chemical outcome of this folding process: acidity, nucleophilicity (of the catalyst), and carbonyl electrophilicity. Overall, this substrate-based folding process generates three different molecular architectures from the same modular functionalities (ketones) and under the same reaction conditions (methyl propiolate and tertiary amine). In addition, and very importantly for combinatorial applications, all of the products share a common reactive functionality that allows them to be collective substrates for a subsequent diversity-generating process.