Development of Synthetic Routes, via a Tropinone Intermediate, to a Long-Acting Muscarinic Antagonist for the Treatment of Respiratory Disease

This contribution describes the development of two synthetic routes to an investigational muscarinic antagonist for the treatment of chronic obstructive pulmonary disease. The first route used a starting material which was in plentiful supply within the GSK network and was used to make material for early clinical trials and safety assessment studies. Further investigations identified a second, potential long-term manufacturing route from commercially available building blocks, using substrate control to install the two stereocentres with excellent selectivity. A key step was a substrate-directed epoxide reduction which also gave rise to a minor byproduct through a skeletal rearrangement of the tropane ring. A deuterium-labeling experiment was carried out, which shed light on the origin of the byproduct, and also guided the improvement of reaction conditions

Development of a Selective Friedel–Crafts Alkylation Surrogate: Safe Operating Conditions through Mechanistic Understanding

This article describes a selective one-pot, Friedel–Crafts acylation/ketone reduction protocol, effectively a surrogate for the Friedel–Crafts alkylation reaction with a primary alkyl halide. A potentially dangerous failure mode was identified, resulting in the uncontrolled evolution of hydrogen. A series of mechanistic experiments, including analysis by ²⁷Al NMR, was undertaken, and the reaction mechanism elucidated. Finally, the use of React IR to ensure real-time reaction safety was demonstrated

Design and Application of a DNA-Encoded Macrocyclic Peptide Library

A DNA-encoded macrocyclic peptide library was designed and synthesized with 2.4 × 10¹² members composed of 4–20 natural and non-natural amino acids. Affinity-based selection was performed against two therapeutic targets, VHL and RSV N protein. On the basis of selection data, some peptides were selected for resynthesis without a DNA tag, and their activity was confirmed