An Efficient Synthesis of Tenofovir (PMPA): A Key Intermediate Leading to Tenofovir-Based HIV Medicines

Herein, we report further improvements to the synthesis of tenofovir 1, the precursor to tenofovir disoproxil fumarate (TDF) and tenofovir alafenamide fumarate (TAF). Starting from acyclic precursor diaminomalononitrile 12, a four-step protocol to tenofovir 1 will allow for vertical integration for more manufacturers. The key transformation is a convergent one-step procedure from 6 as compared to the current commercial process, with an improved yield from 59% (two steps) to 70%. Further improvements include eliminating the need for problematic magnesium tert-butoxide (MTB) and significant solvent reduction by avoiding an intermediate workup. With the costs of HIV/AIDS treatments remaining a barrier for those most in need, lowering the raw material/processing costs and increasing the security of supply can increase patient access.