Gold-Catalyzed Oxidative Reactions of Propargylic Carbonates Involving 1,2-Carbonate Migration: Stereoselective Synthesis of Functionalized Alkenes

A gold-catalyzed oxidative reaction
of propargylic carbonates or
acetates using 3,5-dichloropyridine as the oxidant has been developed.
The reaction provides efficient access to α-functionalized-α,β-unsaturated
ketones with excellent regio- and diastereocontrol via a regioselective
attack of the N-oxide to the gold-activated alkyne
followed by a 1,2-carbonate migration. In addition, the alkene products
could be further transformed into the valuable 5-hydroxycyclopent-2-enones
via cyclocondensation with acetone or cyclodimerization under basic
conditions.