Enantioselective (4+2) Annulation of Donor–Acceptor Cyclobutanes by N‐Heterocyclic Carbene Catalysis |
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| Authors: | Alison Levens Adam Ametovski Prof David W Lupton |
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| Institution: | School of Chemistry, Monash University, Clayton, Victoria, Australia |
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| Abstract: | Herein we report the enantioselective (4+2) annulation of donor–acceptor cyclobutanes and unsaturated acyl fluorides using N‐heterocyclic carbene catalysis. The reaction allows a 3‐step synthesis of cyclohexyl β‐lactones (25 examples) in excellent chemical yield (most ≥90 %) and stereochemical integrity (all >20:1 d.r., most ≥97:3 e.r.). Mechanistic studies support ester enolate Claisen rearrangement, while derivatizations provide functionalized cyclohexenes and dihydroquinolinones. |
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| Keywords: | cyclohexanes donor– acceptor cyclobutanes enantioselective catalysis N-heterocyclic carbenes organocatalysis |
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