atropisomers

Adventures in Atropisomerism: A Case Study from BMS

BMS-986142 is a reversible BTK inhibitor with two axial stereocenters.  BMS synthetic chemists were able to make >200 kilos of this compound as a single isomer using this route.  Wow. Atropisomers are a nightmare in drug discovery.  Axial stereocenters are not easy to set predictably, separation of isomers is a pain, and the products are…