Exploring Homogeneous Conditions for Mild Buchwald–Hartwig Amination in Batch and Flow
Saeed K. Kashani, Jacob E. Jessiman, Stephen G. Newman
Abstract
Cross-couplings are among the most frequently used reactions in complex molecule synthesis. However, the requirement of stoichiometric base can cause challenges. Harsh, insoluble inorganic bases can lead to poor tolerance of sensitive functional groups, scale-up issues, and difficult adaptation to continuous flow platforms. Herein, we describe the use of high throughput experimentation to identify a number of conditions that enable Buchwald–Hartwig reactions to be carried out using readily available ligands (e.g., XantPhos) with DBU as a soluble, functional-group-tolerant, homogeneous base. Application of this system to diverse aminations in batch and flow are demonstrated, as is the translation of this technique to performing continuous Mizoroki–Heck and Sonogashira coupling reactions.