Realisation of small molecule libraries based on frameworks distantly related to natural products.

The availability of high-quality screening compounds is of paramount importance for the discovery of innovative new medicines. Natural product (NP) frameworks can inspire the design of productive compound libraries. Here, we describe the design and synthesis of four compound libraries based on scaffolds that have broad NP-like features, but that are only distantly related to specific NPs. The optimisation of syntheses of the scaffolds using [5 + 2] cycloaddition chemistry is detailed, together with methods to yield exemplar decorated screening compounds. In each case, a library was nominated for production, leading to a total of >2900 screening compounds that augmented the Joint European Compound Library of the European Lead Factory.

A metal-catalyzed enyne-cyclization step for the synthesis of bi- and tricyclic scaffolds amenable to molecular library production.

A facile metal-catalyzed diversification step for the synthesis of novel bi- and tricyclic scaffolds from enyne substrates is reported in this study. From a single starting material, topologically diverse scaffolds for library synthesis can be generated and decorated in a few steps. The methodology was used to produce a library of 490 compounds within the European Lead Factory (ELF) Consortium.

Aminomethylhydroxylation of alkenes: Exploitation in the synthesis of scaffolds for small molecule libraries.

The application of [4+2] cycloadditions between alkenes and an N-benzoyl iminium species, generated in situ under acidic conditions, is described in the synthesis of diverse molecular scaffolds. The key reaction led to the formation of cyclic imidates in good yield and with high regioselectivity. It was demonstrated that the cyclic imidates may be readily converted into 1,3-amino alcohols. Incorporation of orthogonally-reactive functionality, such as aryl and alkyl bromides, into the cycloaddition substrates enabled the synthesis of additional scaffolds. For one scaffold, the synthesis of exemplar screening compounds was undertaken to demonstrate potential value in small molecule library production.

Development of Macrocyclic PRMT5-Adaptor Protein Interaction Inhibitors.

The PRMT5-MEP50 methyltransferase is a major target for anticancer drug discovery, and modulators of its interactions with different regulatory proteins are in high demand because they modulate PRMT5 substrate selectivity. We describe a strategy for the development of a PRMT5/adaptor protein PPI inhibitor, which includes the design and synthesis of macrocyclic peptides based on the motif for the interaction of PRMT5 with its adaptor protein RioK1. After the initial exploration of different macrocycle sizes and cyclization linkages, analysis of a peptide library identified hot spots for the variation of the amino acid structure. The incorporation of nonproteinogenic amino acids into the macrocyclic peptide led to a potent cyclic PRMT5 binding peptide (Ki = 66 nM), which selectively inhibits the interaction of PRMT5 with the adaptor proteins RioK1 and pICln (IC50 = 654 nM) but not with the alternative adaptor protein MEP50. The inhibitor is a promising tool for further biological investigation of this intriguing protein interface.