Asymmetric nitroaldol reaction catalyzed by copper–diamine complexes: selective construction of two contiguous stereogenic centers

Chiral copper(II) complexes of secondary bisamines derived from 1,2-diaminocyclohexane were successfully used in the diastereoselective nitroaldol reaction. The reactions were carried out in the presence of 10 mol % of the Cu(II) complex and 7.7 mol % of i-Pr2NEt in 2-propanol at −30 °C. Good to excellent yields, enantioselectivities of up to 99%, and moderate to excellent diastereoselectivities were obtained for both aromatic or aliphatic aldehydes and various prochiral nitrocompounds forming the corresponding β-nitroalcohols with two contiguous stereocenters.

Figure optionsDownload as PowerPoint slide

(1R,2R)-N,N′-Bis((furan-2-yl)methyl)cyclohexane-1,2-diamineC16H22N2O2[α]D = −57.1 (c 0.2, MeOH)Source of chirality: (1R,2R)-diaminocyclohexaneAbsolute configuration: (R,R)

anti-(1S,2R)-1-(Naphthalen-1-yl)-2-nitropropan-1-olC13H13NO3[α]D = −37.8 (c 0.5, CHCl3, 99% ee)Source of chirality: stereoselective synthesisAbsolute configuration: (1S,2R)