Synthesis of BACE1 Inhibitors E2609/E2071 via Oxime–Olefin Cycloaddition Following a Process Risk Mitigation Strategy

Abstract

Process development of E2609 from the preclinical stage to the clinical stage following a process risk mitigation strategy is described here. Key features include a turbo Grignard reaction monitored by in-situ IR, [3 + 2] cycloaddition in water, chemoselective amide coupling via in-situ protection, and a Reformatsky/decarboxylation approach to install a difluoromethyl group. Toward safe and scalable manufacture of E2071, an analog of E2609, a flow-reaction process for trifluoromethylation of aldehydes is presented here.