Efficient Palladium-Catalyzed Substitution in Enantiomerically Pure Allyl Carbonates – A Stereodivergent Access to β-Aryl-Substituted γ-Lactones and γ-Hydroxy Amides
✍ Scribed by Manfred Braun; Claudia Unger; Kersten Opdenbusch
- Publisher
- John Wiley and Sons
- Year
- 1998
- Tongue
- English
- Weight
- 263 KB
- Volume
- 1998
- Category
- Article
- ISSN
- 1434-193X
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✦ Synopsis
Allyl carbonates (Z)-8 and (E)-9 are available from the converted into (S)-γ-butyrolactone 13 in a three step sequence. When the same protocol is applied to the isomeric addition of the chiral alkenyllithium reagent 5b to aromatic aldehydes 6. When sujected to a palladium-catalyzed diesters 10 and 11, (R)-lactones 13 result. A rationale for the stereochemical outcome of the allylic substitutions in the substitution by sodium malonate, (Z)-carbonates 8 give diesters 10 and 11, whereas (E)-carbonate 9 predominantly carbonates 10-12 is offered, based on π-σ-π interconversions of the palladium complexes 20-23. leads to the diastereomeric product 12. The latter is