Chiral sulfide and achiral sulfonic acid cocatalyzed enantioselective electrophilic tandem selenylation semipinacol rearrangement of allenols

A highly enantioselective electrophilic selenylation/semipinacol rearrangement of allenols has been developed, which is enabled by the cooperative catalysis of a chiral sulfide and an achiral sulfonic acid. The designed and synthesized chiral sulfide catalyst and selenylating reagent play a crucial role in enhancing both enantioselectivity and reactivity. This approach exhibits excellent regio-, chemo-, and enantioselectivity, providing access to diverse enantioenriched cyclopentanones featuring an arylselenovinyl-substituted quaternary carbon stereocenter. Furthermore, these products can be transformed into synthetically valuable alkyne, vinyl bromide, and aniline derivatives. Mechanistic studies reveal that the combination of a chiral sulfide and an achiral sulfonic acid not only facilitates the formation of catalytically active species, but also governs the enantioselectivity of the reaction. Meanwhile, density functional theory calculations disclose that four hydrogen bond interactions and a π‧‧‧π interaction are responsible for the observed enantioselectivity. Rearrangement reactions serve as crucial steps in syntheses of biologically active products and also provide intellectual and conceptual curiosities within the broad field of organic chemistry. Here, the authors report an electrophilic selenylation/semipinacol rearrangement of allenols, catalysed by a chiral Lewis base.