Mechanochemical pyrophosphate bond formation en route to 7-methylguanosine mRNA cap analogs

The growing demand for cleaner and more sustainable synthetic methodologies has brought renewed attention to solid-state chemistry. Within this context, mechanochemistry has emerged as a powerful and versatile strategy. In this study, we report a mechanochemical synthesis of the Anti-Reverse Cap Analog (ARCA), a widely used and commercially available dinucleotide mRNA cap analog commonly used for the preparation of in vitro transcribed mRNAs. Key synthetic steps, including phosphate activation and pyrophosphate bond formation, were successfully carried out under solvent-free milling conditions, whereas 5′-phosphorylation was found to perform better in solution. This approach shortened reaction times, allowed the diphosphate intermediates to be carried forward without isolation, and markedly reduced solvent and reagent consumption, thus providing a greener and more efficient alternative to conventional solution-phase synthesis. Overall, the results demonstrate that mechanochemistry is a viable strategy for more sustainable access to therapeutically relevant mRNA cap analogs.