Copper complexes bearing methylthiophenyl and methylfuranyl derivatives of (R,R)-1,2-diaminocyclohexane: X-ray structures and catalytic exploitation in Henry reaction
作者:Jaewon Cho、Gang Ho Lee、Saira Nayab、Jong Hwa Jeong
DOI:10.1016/j.poly.2015.07.023
日期:2015.10
Two novel dichloro Cu(II) complexes of (R,R)-N-1,N-2-bis((5-methylthiophen-2-yl)methyl)cyclohexane-1,2-diamine (MTCHD) and (R,R)-N-1,N-2-bis((5-methylfuran-2-yl)methyl)cyclohexane-1,2-diamine (MFCHD) ligands have been synthesised and structurally characterised using X-ray diffraction. The geometry around the Cu(II) centres was distorted square planner. A strong Cu center dot center dot center dot O-furanyl interaction exists in Cu(MFCHD)Cl-2 that leads to the disappearance of original C-2-symmetry of the ligand, resulting in selective R,S-coordination of N atoms in (1R,2R)-1,2-diaminocyclohexane. Catalytic activities of dichloro and diacetato Cu(II) complexes with 3 mol% of iPr(2)NEt were assessed in asymmetric Henry reactions that resulted in moderate to high yields with an enantiomeric excess up to 92%, without air/moisture exclusion. (C) 2015 Elsevier Ltd. All rights reserved.