Oseltamivir phosphate (Tamiflu) was synthesized from d-mannose through a short and practical synthetic route. A unique feature of the route is that the bulky 3-pentyloxy group and adjacent acetamide of Tamiflu were introduced at an early stage of the synthesis by copper- catalyzed regioselective ring-opening of the 2, 3-pentylidene ketal of d-lyxofuranoside. The d-lyxofuranoside ethylphosphonate precursor was then cyclized via an intramolecular ...
