Conditions-Controlled Divergent Annulation of Bicyclo[1.1.0]butanes and Dioxopyrrolidines through Lewis Acid Catalysis

The divergent construction of unique ring systems poses
a substantial
challenge in organic chemistry. Herein, we describe the Lewis acid-catalyzed
divergent annulations of bicyclo[1.1.0]butanes and dioxopyrrolidines.
By precisely modulating the catalytic conditions, the identical substrates
are directed to selectively undergo one of three different annulation
pathways: (3 + 2), (3 + 4), or (2 + 4) cyclizations. This method facilitates
the swift construction of diverse and unique ring systems, such as
bicyclo[2.1.1]hexanes, oxabicyclo[4.1.1]octanes, and cyclobutanes,
which are further amenable to various functional group transformations.
Additionally, preliminary mechanistic studies have shed light on the
basis of the observed reaction divergence.