Formation of 2-alkylidene-1,3-diones and .alpha.,.beta.-unsaturated ketones from the pyrolysis of propargyl esters

Mercuric Triflate-Catalyzed Reaction of Propargyl Acetates with Water Leading Vinyl Ketones

“…In this communication, we describe the reaction of propargyl acetate and water to give vinyl ketones under very mild conditions, catalyzed by mercury(II) trifluoromethanesulfonate [mercuric triflate, hereafter referred to as Hg(OTf) 2 ], as an alternative to the Meyer−Schuster and Rupe rearrangement applicable to primary alcohols, although the mechanism is entirely different. Conversion of primary propargyl alcohols to vinyl ketones was reported by Yadav using 6 equiv of Hg(OAc) 2 followed by H 2 S treatment 2a and by Alami using CF 3 CO 2 H at 100 °C 2b. Trahanovsky also reported enone synthesis by pyrolysis of propargyl esters at very high temperature (around 650 °C) 2c.…”

“…Conversion of primary propargyl alcohols to vinyl ketones was reported by Yadav using 6 equiv of Hg(OAc) 2 followed by H 2 S treatment 2a and by Alami using CF 3 CO 2 H at 100 °C 2b. Trahanovsky also reported enone synthesis by pyrolysis of propargyl esters at very high temperature (around 650 °C) 2c. We originally developed Hg(OTf) 2 as a highly efficient olefin cyclization agent, and we applied it to the synthesis of polycyclic terpenoids .…”