Asymmetric Aldol Reactions Using (S,S)-(+)-Pseudoephedrine-Based Amides: Stereoselective Synthesis of α-Methyl-β-hydroxy Acids, Esters, Ketones, and 1,3-Syn and 1,3-Anti Diols
- 20 May 2000
- journal article
- research article
- Published by American Chemical Society (ACS) in The Journal of Organic Chemistry
- Vol. 65 (12), 3754-3760
- https://doi.org/10.1021/jo000035h
Abstract
A very efficient method for performing stereoselective aldol reactions is reported. The reaction of (S, S)-(+)-pseudoephedrine-derived propionamide enolates with several aldehydes yielded exclusively one of the four possible diastereomers in good yields, although transmetalation of the firstly generated lithium enolate with a zirconium(II) salt, prior to the addition of the aldehyde, is necessary in order to achieve high syn selectivity. The so-formed syn-alpha-methyl-beta-hydroxy amides were transformed into other valuable chiral nonracemic synthons such as alpha-methyl-beta-hydroxyacids, esters, and ketones. Finally, a stereocontrolled reduction procedure starting from the so-obtained alpha-methyl-beta-hydroxy ketones has been developed allowing the synthesis of either 1,3-syn- or 1,3-anti-alpha-methyl-1,3-diols in almost enantiopure form by choosing the appropriate reaction conditions.Keywords
This publication has 19 references indexed in Scilit:
- Design and Evaluation of a Practical Camphor-Based Methyl Ketone Enolate for Highly Stereoselective “Acetate” Aldol ReactionsAngewandte Chemie-International Edition, 1998
- Synthesis of a novel chiral 1, 3-benzoxazinone auxiliary and its application to highly diastereoselective aldol reactionTetrahedron Letters, 1996
- Toward the development of a general chiral auxiliary 2. Evaluation of camphor lactam imide auxiliaries for asymmetric aldol reactionsTetrahedron Letters, 1994
- Efficient asymmetric synthesis of anti-aldols from bornanesultam derived boryl enolatesTetrahedron Letters, 1993
- Diastereo‐ and Enantioselective Synthesis of C2‐Symmetrical HIV‐1 Protease InhibitorsAngewandte Chemie-International Edition, 1993
- A new class of recoverable chiral sulphoxide: Application to the asymmetric synthesis of β-hydroxy esters.Tetrahedron Letters, 1992
- Anti‐Selective and Diastereofacially Selective Aldol Reactions with (R)‐2‐Siloxy‐1,2,2‐triphenylethyl propionateAngewandte Chemie-International Edition, 1991
- Asymmetric aldol reactions. A new camphor-derived chiral auxiliary giving highly stereoselective aldol reactions of both lithium and titanium(IV) enolatesJournal of the American Chemical Society, 1991
- Bornane sultam-directed asymmetric synthesis of crystalline, enantiomerically pure syn aldolsJournal of the American Chemical Society, 1990
- Enantio‐ and anti‐Diastereoselective Aldol Additions of Acetates and Propionates via O‐Silyl Ketene AcetalsAngewandte Chemie-International Edition, 1985