Synthesis of chiral 1,3-diamines derived from cis-2-benzamidocyclohexanecarboxylic acid and their application in the Cu-catalyzed enantioselective Henry reaction.
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.
Department of Applied Chemistry, Graduate School of Science and Engineering, Saitama University, 255 Shimo-Okubo, Saitama 338-8570, Japan. kodama@mail.saitama-u.ac.jp
Koichi
K
Kodama
Kazuyuki
K
Sugawara
Takuji
T
Hirose
D001549:Benzamides / Q000737:chemistry*; D002384:Catalysis; D003300:Copper / Q000737:chemistry*; D003510:Cyclohexanes / Q000737:chemistry*; D003959:Diamines / Q000138:chemical synthesis* / Q000737:chemistry*; D008024:Ligands; D015394:Molecular Structure; D013237:Stereoisomerism
D001549:Benzamides; D003510:Cyclohexanes; D003959:Diamines; D008024:Ligands; C571094:cis-2-benzamidocyclohexanecarboxylic acid; D003300:Copper