Enol triflates derived from the Wieland–Miescher ketone and an analog bearing an angular acetoxymethyl group: their highly regioselective synthesis and Stille coupling with vinyl(tributyl)tin

• Published in: Tetrahedron letters 2006-06, Vol.47 (26), p.4331-4335
• Main Authors: Zorn, Nicolas, Lett, Robert
• Format: Article
• Language: English
• ISSN: 0040-4039; 1873-3581
• DOI: 10.1016/j.tetlet.2006.03.185

A highly selective synthesis of the enol triflate derived from the 9-keto group was achieved directly from diketones in kinetic conditions. The isomeric triflates were also prepared selectively in other conditions (kinetic or thermodynamic) and their specific Stille couplings achieved. A highly selective synthesis of the enol triflate derived from the 9-keto group was achieved directly from the Wieland–Miescher ketone or an analog in kinetic conditions with LHMDS/THF–HMPA and Comins reagent. The other isomeric triflates were also obtained selectively in other conditions and their specific Stille coupling with vinyl(tributyl)tin was achieved in high yields. The structures of the different isomers were determined unambiguously by IR, UV, 1H and 13C NMR (COSY, HMBC, HSQC, and NOE). The results previously reported by Pal for the Wieland–Miescher ketone have therefore to be corrected, due to erroneous structural assignments.