Diastereoselective Darzens Condensations.
โ Scribed by Thierry J. R. Achard; Yuri N. Belokon; Jamie Hunt; Michael North; Francesca Pizzato
- Publisher
- John Wiley and Sons
- Year
- 2007
- Weight
- 33 KB
- Volume
- 38
- Category
- Article
- ISSN
- 0931-7597
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๐ SIMILAR VOLUMES
Sumunary: --\_-Enantiomerically pure benzyl cis-a,B-epoxycarboxylates were prepared by a modified Darsens procedure utilizing aldx condensation reactions of chiral a-haloimidates with various aldehydes. A unique chirality reversal was observed using Zincenolates.
The reaction of tin enolates of cyclohexanone or propiophenone with benzaldehyde at -78'C gives predominately the threo aldol diastereomer.
The catalytic asymmetric Darzens condensation promoted by the quaternary ammonium salt (PTC A) derived from cinchonine as a phase-transfer catalyst is described. Treatment of phenacyl chloride with various aldehydes under mild reaction conditions afforded the corresponding desired product in good yi