Heterocyclic Spiranes and Dispiranes <i>via</i> Enantioselective Phosphine‐Catalyzed [3+2] Annulations

Abstract

Abstract The synthesis of highly functionalized heterocyclic spiranes has been carried out by [3+2] cyclizations between allenoates and enones, under phosphine catalysis. Excellent enantioselectivity levels ( ee s up to 99%) have been attained in FerroPHANE‐promoted cyclizations of this class, leading to chiral sulfides with unprecedented spiranic structures. The corresponding sulfoxides have been obtained then via a subsequent, highly diastereoselective oxidation of the prostereogenic sulfur centre.