Functionalized Periodic Mesoporous Organosilica: A Highly Enantioselective Catalyst for the Michael Addition of 1,3-Dicarbonyl Compounds to Nitroalkenes

• Published in: Chemistry : a European journal Vol. 18; no. 48; pp. 15546 - 15553
• Main Authors: Liu, Ketang, Jin, Ronghua, Cheng, Tanyu, Xu, Xiangming, Gao, Fei, Liu, Guohua, Li, Hexing
• Format: Journal Article
• Language: English
• Published: Weinheim WILEY-VCH Verlag 26.11.2012; WILEY‐VCH Verlag; Wiley; Wiley Subscription Services, Inc
• Subjects: asymmetric catalysis; Catalysts; Chemistry; Chemistry, Multidisciplinary; heterogeneous catalysis; immobilization; mesoporous materials; Michael addition; Physical Sciences; Science & Technology; Michael addition; immobilization; heterogeneous catalysis; MECHANISM; SCOPE; TRANS-(1R,2R)-DIAMINOCYCLOHEXANE; TRANSFER HYDROGENATION; ALDEHYDES; asymmetric catalysis; KETONES; ORGANOCATALYSTS; mesoporous materials; SILICA; CONJUGATE ADDITION
• ISSN: 0947-6539; 1521-3765
• DOI: 10.1002/chem.201202407

A functionalized periodic mesoporous organosilica with incorporated chiral bis(cyclohexyldiamine)‐based NiII complexes within the silica framework was developed by the co‐condensation of (1R,2R)‐cyclohexyldiamine‐derived silane and ethylene‐bridge silane, followed by the complexation of NiBr2 in the presence of (1R,2R)‐N,N′‐dibenzylcyclohexyldiamine. Structural characterization by XRD, nitrogen sorption, and TEM disclosed its orderly mesostructure, and FTIR and solid‐state NMR spectroscopy demonstrated the incorporation of well‐defined single‐site bis(cyclohexyldiamine)‐based NiII active centers within periodic mesoporous organosilica. As a chiral heterogeneous catalyst, this functionalized periodic mesoporous organosilica showed high catalytic activity and excellent enantioselectivity in the asymmetric Michael addition of 1,3‐dicarbonyl compounds to nitroalkenes, comparable to those with homogeneous catalysts. In particular, this heterogeneous catalyst could be recovered easily and reused repeatedly up to nine times without obviously affecting its enantioselectivity, thus showing good potential for industrial applications. A pore show: Functionalized periodic mesoporous organosilicas (PMOs) with incorporated chiral NiII complexes exhibited high catalytic activity and enantioselectivity in the asymmetric Michael addition of 1,3‐dicarbonyl compounds to nitroalkenes (see scheme; DACH=diaminocyclohexane).