Rhodium-catalyzed enantioselective addition to unsymmetrical α-diketones: tandem one-pot synthesis of optically active 3-tetrasubstituted isochroman derivatives.

The domino effect: An efficient and general catalytic one-pot synthesis of quaternary-substituted isochroman derivatives has been developed (see scheme). The cascade transformation relies on rhodium-catalyzed highly regio- and enantioselective 1,2-addition of arylboronic acids to unsymmetrical α-diketones and intramolecular etherification or esterification, and provides a variety of enantioenriched isochromanones under exceptionally mild conditions.