© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. We report a synthetic strategy for a chemoselective switch and a diastereo-divergent approach for the asymmetric reaction of 5H-oxazol-4-ones and N-itaconimides catalyzed by L-tert-leucine-derived tertiary amine-urea compounds. The reaction was modulated to harness either tandem conjugate addition-protonation or [4+2] cycloaddition as major product with excellent enantio- and diastereoselectivities. Subjecting the enantio-enriched cycloaddition products to a basic silica gel reagent yields the diastereomer vis-à-vis the product directly obtained under conditions for addition-protonation, thus opening a diastereo-divergent route for creating 1,3-tertiary-hetero-quaternary stereocenters. Quantum chemical studies further provide stereochemical analysis for the [4+2] process and a plausible mechanism for this chemoselective switch is proposed.
|Original language||English (US)|
|Number of pages||5|
|Journal||Angewandte Chemie International Edition|
|State||Published - Dec 9 2015|
Bibliographical noteKAUST Repository Item: Exported on 2020-10-01
Acknowledgements: Z.J. is grateful for the grants from NSFC (grant number21072044), NCET-11-0938 and the Program for InnovativeResearch Team from the University of Henan Province(14IRTSTHN006). M.L.C. gratefully acknowledges generousallocations of supercomputing time on the National Facility ofthe National Computational Infrastructure, and financialsupport from the Australian Research Council. R.L. alsoacknowledges Dr. Xiaohe Miao (KAUST) for supplementarycomputing time.
This publication acknowledges KAUST support, but has no KAUST affiliated authors.