Highly enantioselective Henry (nitroaldol) reaction of aldehydes and alpha-ketoesters catalyzed by N,N'-dioxide-copper(I) complexes.
A new chiral N,N'-dioxide-Cu(I) catalyst has been developed for the asymmetric Henry (nitroaldol) reaction. The approach benefited from the easy modification of the chiral space. As the highly effective N-oxide ligand, 1d has been adopted for the Henry reaction with both aromatic and heteroaromatic aldehydes. The corresponding nitro-alcohol products were obtained in good yields with high enantiomeric excesses up to 98%. Moreover, alpha-ketoesters were also catalyzed by this catalyst to give attractive optically active alpha-hydroxy beta-nitro esters containing chiral quaternary carbon centers (up to 99% ee). On the basis of a combination of several techniques including the 1H NMR, ESI-HRMS, and MM2 calculations, the proposed mechanism was presented to explain the origin of reactivity and asymmetric inductivity.
Qin
Bo
B
Key Laboratory of Green Chemistry & Technology (Sichuan University), Ministry of Education, College of Chemistry, Sichuan University, Chengdu, China.
Xiao
Xiao
X
Liu
Xiaohua
X
Huang
Jinglun
J
Wen
Yuehong
Y
Feng
Xiaoming
X
D000447:Aldehydes / Q000737:chemistry*; D000465:Algorithms; D002384:Catalysis; D003300:Copper / Q000737:chemistry*; D004952:Esters / Q000737:chemistry*; D007659:Ketones / Q000737:chemistry*; D008024:Ligands; D009682:Magnetic Resonance Spectroscopy; D009574:Nitro Compounds / Q000737:chemistry*; D009942:Organometallic Compounds / Q000737:chemistry*; D010087:Oxides / Q000737:chemistry*; D021241:Spectrometry, Mass, Electrospray Ionization
D000447:Aldehydes; D004952:Esters; D007659:Ketones; D008024:Ligands; D009574:Nitro Compounds; D009942:Organometallic Compounds; D010087:Oxides; D003300:Copper