One-Pot and Sequential Asymmetric Hydrogenation of β,δ-Diketoesters into Functionalized 1,3-Diols: From anti- to syn-Stereoselectivity
✍ Scribed by Véronique Blandin; Jean-François Carpentier; André Mortreux
- Publisher
- John Wiley and Sons
- Year
- 1999
- Tongue
- English
- Weight
- 335 KB
- Volume
- 1999
- Category
- Article
- ISSN
- 1434-193X
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✦ Synopsis
The asymmetric hydrogenation of methyl 3,5-syn-2 in up to 92% de but with poor enantiomeric excesses. In all cases, methyl (R)-3-hydroxy-5-oxohexanoate [(R)-11] is dioxohexanoate (1) into mixtures of 3,5-dihydroxyesters (2) and 3-hydroxylactones (3) has been reinvestigated with a the exclusive primary hydrogenation product, which can be isolated in high yields and enantiomeric excesses up to 78%. variety of ruthenium catalysts. Catalysts bearing diphosphanes which possess axial chirality such as (S)-MeO-Further hydrogenation of enantiomerically enriched (R)-11 in a separate experiment affords (3R,5R)-syn-2 in high Biphep give predominantly (3R,5S)-anti-2 in up to 78% de and 95% ee, affording an efficient synthesis of (S)-6-methyl-diastereomeric and enantiomeric excesses (up to 80% and 98%, respectively), provided a Ru-(R)-Binap-type catalyst is 5,6-dihydro-2-pyrone [(S)-5] in up to 95% enantiomeric excess. On the contrary, some Ru-{amidophosphane-used. phosphinite} complexes catalyze sluggishly the formation of outcome of the reaction was expected not to be simple. The