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DOI: 10.1055/s-2008-1042701
1,2,3-Trisubstituted Indanes via Tandem Conjugate Additions
Contributor(s):Mark Lautens, Frédéric MénardUniversidad Complutense, Madrid, Spain
Stereoselective Rh(I)-Catalyzed Tandem Conjugate Addition of Boronic Acids-Michael Cyclization
Org. Lett. 2008, 10: 217-219
Publication History
Publication Date:
21 February 2008 (online)
Key words
indanes - tandem reaction - rhodium
Significance
The method provides a simple way to prepare highly substituted indane molecules. In one domino sequence, a boronic acid added to the unsaturated system and the resulting enolate cyclizes on the pendant second Michael acceptor. The diastereoselectivity observed was good and favored the thermodynamically more stable all-trans product. Though esters were not suitable substrates for the reaction, the authors showed that they could still be accessed via a Baeyer-Villiger oxidation of the phenyl ketones.
Review
L. F. Tietze, G. Brasche, K. Gericke In Domino Reactions in Organic Synthesis; Wiley-VCH: Weinheim, 2006, 631.
Comment
In cases where the Michael acceptors were different (R1 ∂ R2), the initial addition occurred on the system with the lowest LUMO, i.e. phenyl over methyl ketone. Since the relative stereochemistry is controlled by an irreversible initial addition of the organorhodium nucleophile, it should be possible to obtain the cyclized product enantioselectively with the same level of diastereoselectivity - especially in view of the success of Hayashi’s work with similar systems (T. Hayashi, K. Yamasaki Chem. Rev. 2003, 103, 2829).