Masson-Makdissi J,
Prieto L,
Abel-Snape X,
Lautens M.
*
University of Toronto, Canada
Enantio- and Diasterodivergent Sequential Catalysis Featuring Two Transition-Metal-Catalyzed
Asymmetric Reactions.
Angew. Chem. Int. Ed. 2021;
60: 16932-16936
DOI:
10.1002/anie.202105800
Key words
palladium catalysis - rhodium catalysis - diastereodivergent synthesis
Significance
The authors report enantio- and diastereodivergent synthesis of ketones with two
remote stereocenters using Pd-catalyzed asymmetric allylic alkylation and Rh-catalyzed
1,4-addition in a sequential manner. Although these reaction were reported previously,
additional screening had to be done to find similar reaction conditions and ensure
compatibility of catalysts. These reactions independently gave only good enantioselectivities.
Comment
A complete one-pot process in which all reagents are present from the beginning of
the reaction underperformed. It was found that too much methanol as well as phenylboronic
acid interfered with the Pd-catalyzed asymmetric allylic alkylation, decreasing both
conversion and ee. Finally, the process was used to prepare all four stereoisomers
of the cyclohexenone in good yield (65–73%) and excellent enantioselectivity (99%
ee).
