Synthesis of Chiral 1,3-Diamines Derived from cis-2-Benzamidocyclohexanecarboxylic Acid and Their Application in the Cu-Catalyzed Enantioselective Henry Reaction
✍ Scribed by Dr. Koichi Kodama; Kazuyuki Sugawara; Prof. Takuji Hirose
- Publisher
- John Wiley and Sons
- Year
- 2011
- Tongue
- English
- Weight
- 438 KB
- Volume
- 17
- Category
- Article
- ISSN
- 0947-6539
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✦ Synopsis
Abstract
In this study, 13 different chiral 1,3‐diamines were synthesized from (−)‐cis‐2‐benzamidocyclohexanecarboxylic acid. They were successfully applied as ligands in the Cu‐catalyzed asymmetric Henry reaction between benzaldehyde and nitromethane. It was confirmed that the enantioselectivity of the product could be controlled by the substituents on the two amino groups. A time‐course study revealed a decrease in product enantioselectivity caused by spontaneous retro‐Henry reaction, which was suppressed by conducting the reaction at 0 °C. This versatile reaction afforded various β‐nitroalcohols in excellent yields and enantioselectivities (up to 98 % yield, 91 % enantiomeric excess) under the optimized reaction conditions. The chiral induction mechanism was explained on the basis of a previously proposed transition‐state model.