Stereoselective Synthesis of 1,2,3‐Trisubstituted 1,3‐Dienes through Novel [3,3]‐Sigmatropic Rearrangements in α‐Allenic Methanesulfonates: Application to the Preparation of Fused Tricyclic Systems by Tandem Rearrangement/Diels−Alder Reaction | Publicación