Boronic Acid-Catalyzed, Highly Enantioselective Aza-Michael Additions of Hydroxamic Acid to Quinone Imine Ketals

Boronic
acid is one of the most versatile organic molecules in
chemistry. Its uses include organic reactions, molecular recognition,
assembly, and even medicine. While boronic acid catalysis, which utilizes
an inherent catalytic property, has become an important research objective,
it still lags far behind other boronic acid chemistries. Here, we
report our discovery of a new boronic acid catalysis that enables
the aza-Michael addition of hydroxamic acid to quinone imine ketals.
By using 3-borono-BINOL as a chiral boronic acid catalyst, this reaction
could be implemented in a highly enantio­selective manner, paving
the way to densely functionalized cyclohexanes.