Enantioselective aldol condensations. 2. Erythro-selective chiral aldol condensations via boron enolates
โ Scribed by Evans, D. A.; Bartroli, J.; Shih, T. L.
- Book ID
- 115466468
- Publisher
- American Chemical Society
- Year
- 1981
- Tongue
- English
- Weight
- 412 KB
- Volume
- 103
- Category
- Article
- ISSN
- 0002-7863
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๐ SIMILAR VOLUMES
A/do/ condensation of chiraal ethylketones 8 and 9,via their 9-BBN or "BupB eno/ates,with methacrolein and acetaldehyde gives mainly the &&&I adduct, 8 -+ 14 or 9 + 18. The chiral reagent (+)-(lpc)~OTf, in the presence of EL& is used to enhance the formation of 14 and 78, while
Titanium enolates derived from ketones and esters react with aldehydes to afford erythro adducts with high diastereoselection.
Aldol condensation between diethylketone and simple aldehydes using (lpc)2BOTfliPr2NEt in CH,CI, gives syn-adducts in good ee (66-90%) and with high diastereoselectivity (290%). Other chiral dialkylboron triflate reagents examined give lower ees. The aldol condensation reaction of boron enolates, l