Telescoped Two-Step Continuous-Flow Synthesis of Nevirapine Enabled by the On-Demand Generation of NaHMDS

Abstract A telescoped two-step fully continuous-flow process for the synthesis of nevirapine (trade name: Viramune), a key therapeutic agent for the prevention and treatment of HIV-1 infection, has been developed. The process employs, for the first time, sodium bis(trimethylsilyl)amide (NaHMDS) as a homogeneous, process-friendly base for both reaction stages and enables direct conversion of methyl 2-(cyclopropylamino)nicotinate and 2-chloro-3-amino-4-picoline to nevirapine without isolation of the cyclization intermediate. The optimized process operates with a total residence time of 10 min and delivers crude nevirapine in 91.9% overall isolated yield across two reaction steps, with a space-time yield of ∼365 g/h/L and 99.6 A% HPLC purity. Furthermore, we developed an on-demand continuous generation of NaHMDS in diglyme (up to ∼2.0 M) using a sodium packed-bed column reactor. Using on-demand generated NaHMDS, the telescoped synthesis yielded crude nevirapine in 90.7% isolated yield (∼340 g/h/L space-time yield and 99.5 A% purity), providing a scalable and cost-effective alternative to NaH applied in the current commercial synthesis.