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Published on: May 26, 2019
Isochalcogenourea-catalyzed asymmetric (4 + 2)-heterocycloadditions of allenoates
1Institute of Organic Chemistry, Johannes Kepler University Linz, Altenbergerstrasse 69, 4040 Linz, Austria.
Abstract:
Allenoates are versatile reagents that can be used for numerous (formal) cycloaddition reactions under (chiral) Lewis base catalysis. Most commonly, the catalysts of choice are phosphines, amines, and N-heterocyclic carbenes. We have recently established the use of readily available chiral isochalcogenoureas as catalysts for asymmetric (4 + 2)-heterocycloadditions of allenoates with various vinylogous acceptors. This represents a complementary approach for allenoate activation and gives access to various highly functionalized chiral dihydropyrans with good to excellent enantioselectivities and diastereoselectivities.
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