Deucravacitinib (BMS-986165) is a deuterated small-molecule TYK2 inhibitor developed for the treatment of numerous autoimmune disorders. While the first-generation discovery chemistry route to access deucravacitinib was concise and sufficient to access kilogram quantities of API, impurity control and cost-of-goods concerns necessitated the design of a new route. Once a new route was identified and demonstrated, each step was optimized for yield, purity, robustness, and sustainability. Key accomplishments include (1) the development of a novel cyclocondensation under mild conditions to afford a methylated 1,2,4-triazole with excellent regiocontrol, (2) the development of safe, homogeneous conditions to quench POCl3 following chlorination of a substrate that is sensitive to nucleophilic and basic conditions, (3) the discovery of a robust, scalable “dual-base” palladium-catalyzed C–N coupling reaction, and (4) mechanistic understanding to inform control strategies for a number of process-related impurities in an API step amidation mediated by EDC. Ultimately, the optimized commercial route was successfully scaled up to afford more than a metric ton of deucravacitinib for clinical and commercial use.