Rhodium-Catalyzed Asymmetric Tandem Cyclization for Efficient and Rapid Access to Underexplored Heterocyclic Tertiary Allylic Alcohols Containing a Tetrasubstituted Olefin

The
first Rh-catalyzed asymmetric tandem cyclization of nitrogen-
or oxygen-bridged 5-alkynones with arylboronic acids was achieved.
The simple catalytic system involving a rhodium­(I) complex with readily
available chiral BINAP ligand promotes the reaction to proceed in
a highly stereocontrolled manner. This protocol provides a very reliable
and practical access to a variety of chiral heterocyclic tertiary
allylic alcohols possessing a tetrasubstituted carbon stereocenter
and an all-carbon tetrasubstituted olefin functionality in good yields
with great enantioselectivities up to 99% ee.