Copper complexes bearing methylthiophenyl and methylfuranyl derivatives of (R, R)-1, 2-diaminocyclohexane: X-ray structures and catalytic exploitation in Henry reaction. (15th October 2015)

• Record Type: Journal Article
• Authors: Cho, Jaewon; Lee, Gang Ho; Nayab, Saira; Jeong, Jong Hwa
• Is Part Of: Polyhedron. Volume 99(2015)
• Page Start: 198
• Page End: 203
• Publication Date: 2015-10-15
• Subjects: Enantiopure N, N-diamine -- Copper complexes -- R, S-coordination N, N-diamine -- Enantioselective Henry reaction; Chemistry, Inorganic -- Periodicals; Chimie inorganique -- Périodiques; Organometaalverbindingen; Anorganische chemie; 546.05
• DOI: 10.1016/j.poly.2015.07.023
• Languages: English
• ISSNs: 0277-5387

Abstract

Graphical abstract: Novel Cu complexes ligated to methylthiophenyl and methylfuranyl derivatives of ( R, R )-1, 2-diaminocyclohexane were synthesized and characterized by X-ray diffraction. The original C 2 -symmetry was lost upon complexation to Cu(II) centre and resulted in selective R, S -coordination of N atoms in case of furanyl containing ligand. The dichloro and diacetato derivatives proved to be active catalysts in asymmetric Henry reaction with moderate yields and enantioselectivities up to 92%. Abstract: 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…Ofuranyl interaction exists in Cu(MFCHD)Cl2 that leads to the disappearance of original C 2 -symmetry of the ligand, resulting in selective R, S- coordination of N atoms in (1 R, 2 R )-1, 2-diaminocyclohexane. Catalytic activities of dichloro and diacetato Cu(II) complexes with 3 mol% of i Pr2 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.