A Versatile and Highly Stereoselective Access to Vinyl Triflates Derived from 1,3-Dicarbonyl and Related Compounds

1,3-Dicarbonyl derivatives, such as 1,3-diketones, β-ketoaldehydes, β-ketoesters, β-ketoamides, β-ketophosphonates and β-ketosulfones were efficiently converted to the corresponding Z vinyl triflates with high stereoselectivity. Precoordination with lithium triflate in dichloromethane and enolization with mild bases such as trialkylamines or DBU followed by trapping with triflic anhydride probably accounted for such high selectivity, achieved even at 0 °C. This method offers the first direct route to vinyl triflates from β-ketoamides, β-ketophosphonates and β-ketosulfones.