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Stereodivergent Organocatalytic Intramolecular Michael Addition/Lactonization for the Asymmetric Synthesis of Substituted Dihydrobenzofurans and Tetrahydrofurans |
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| Authors: | Dorine Belmessieri Alix de la Houpliere Ewen D. D. Calder Dr. James E. Taylor Prof. Andrew D. Smith |
| Affiliation: | EaStCHEM, School of Chemistry, University of St. Andrews, North Haugh, St. Andrews, KY16 9ST (UK) |
| Abstract: | A stereodivergent asymmetric Lewis base catalyzed Michael addition/lactonization of enone acids into substituted dihydrobenzofuran and tetrahydrofuran derivatives is reported. Commercially available (S)‐(?)‐tetramisole hydrochloride gives products with high syn diastereoselectivity in excellent enantioselectivity (up to 99:1 d.r.syn/anti, 99 % eesyn), whereas using a cinchona alkaloid derived catalyst gives the corresponding anti‐diastereoisomers as the major product (up to 10:90 d.r.syn/anti, 99 % eeanti). |
| Keywords: | asymmetric catalysis cinchona alkaloid isothiourea Michael addition organocatalysis oxygen heterocycles stereodivergent |