The microwave-assisted organocatalyzed rearrangement of Propargyl vinyl ethers to salicylaldehydes derivatives

Propargyl vinyl ethers constitute a privileged group of small size, densely functionalized and readily accessible linear scaffolds. The main key to the chemical reactivity encoded in these structures is the [3,3]-sigmatropic rearrangement (propargyl Claisen rearrangement) shown in Scheme 1A, which takes place irreversibly and under thermodynamic control to generate the allene 2 which isomerizes to dienal. We have developed a microwave-assisted, catalytic (imidazole 10 mol-%) and scalable methodologyto transform these allenes into salicylaldehyde motives supported on a broad range of topologies, which spanned from simple aromatic monocycles to complex fused polycyclic systems. The reaction manifold is depicted in Scheme 1B. We have performed a theoretical study of this reaction which is in full agreement with the observed experimental results. The reaction scope and the proposed mechanism will be commented in our presentation.