An improved procedure for the synthesis of fourteen 4-OH and 3-MeO-4OH metabolites of fentanyl analogues from two intermediates on multi-gram scale

• Published in: Synthetic communications 2022-02, Vol.52 (3), p.392-401
• Main Authors: Rautio, Tobias, Thornell, Jonathan, Gréen, Henrik, Konradsson, Peter, Dahlén, Johan, Wu, Xiongyu
• Format: Article
• Language: English
• Subjects: Fentanyl analogues; key intermediate; metabolite; Metabolites; multigram scale; Purification; Silica gel; Synthesis; Toxicology
• ISSN: 0039-7911; 1532-2432; 1532-2432
• DOI: 10.1080/00397911.2022.2026396

Fentanyl analogues have appeared on the recreational drug market during the last ten years and caused many fatal overdoses around the world due to their high potencies. Their metabolites are of great interest for toxicology, metabolism and identification studies. According to the literature, fentanyl analogues with similar structures have similar metabolism profile. Therefore, a synthetic route that enables synthesis of the corresponding metabolites for several fentanyl analogues would be valuable. Fentanyl analogue metabolites are often polar and tailing on silica gel. Hence, the purification of these substances could be challengeable. In this work, a general synthetic route was developed and described for the multi-gram scale synthesis of 14 potential metabolites of seven fentanyl analogues. The synthetic route is concise and optimized, does not require any use of silica gel purification and is therefore convenient for large-scale synthesis. The overall yields of the metabolites were in the range of 25-57%.