Enantioselective Synthesis of Tricyclic β‑Lactones by NHC-Catalyzed Desymmetrization of Cyclic 1,3-Diketones
journal contributionposted on 01.07.2020, 20:15 by Sayan Shee, Subrata Mukherjee, Rajesh G. Gonnade, Akkattu T. Biju
The NHC-catalyzed desymmetrization of cyclic-1,3-diketones allowing the enantioselective construction of tricyclic β-lactones with five contiguous stereocenters, including two quaternary stereocenters, has been developed. The mild and operationally simple addition of α-bromoenals to cyclopentane-1,3-diketone derivatives proceeds via the initial formation of chiral α,β-unsaturated acylazolium intermediates and culminates in a cascade reaction, following the Michael-aldol-lactonization pathway to deliver the β-lactone derivatives in moderate to good yields and excellent selectivity.
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Michael-aldol-lactonization pathwayselectivityDiketoneLactoneproceedNHC-Catalyzed DesymmetrizationCycliccyclopentaneformationacylazolium intermediatesα- bromoenalsβ- lactone derivativestricyclic β- lactoneschiralTricyclicquaternary stereocentersyieldNHC-catalyzed desymmetrizationcascade reactionenantioselective constructionEnantioselective Synthesis