Dual Chalcogen–Chalcogen Bonding Catalysis

The noncovalent S···O
bonding interaction is an
evolutionary force that has been smartly exploited by nature to modulate
the conformational preferences of proteins. The employment of this
type of weak noncovalent force to drive chemical reactions is promising
yet remains largely elusive. Herein, we describe a dual chalcogen–chalcogen
bonding catalysis strategy that the distinct chalcogen atoms simultaneously
interact with two chalcogen-based electron donors to give rise to
the catalytic activity, thus facilitating chemical reactions. Conventional
approaches to the Rauhut–Currier-type reactions require the
use of strongly nucleophilic Lewis bases as essential promoters. The
implementation of this dual chalcogen–chalcogen bonding catalysis
strategy allows the simultaneous Se···O bonding interaction
between chalcogen-bonding donors and an enone and an alcohol, enabling
the realization of the Rauhut–Currier-type reactions in a distinct
way. The further implementation of a consecutive dual Se···O
bonding catalysis approach enables the achievement of an initial Rauhut–Currier-type
reaction to give an enone product which further undergoes an alcohol-addition
induced cyclization reaction. This work demonstrates that the nearly
linear chalcogen-bonding interaction can differentiate similar alkyl
groups to give rise to regioselectivity. Moreover, the new strategy
shows its advantage as it not only enables less reactive substrates
working efficiently but tolerates inaccessible substrates using conventional
methods.