Half-Sandwich Ruthenium Complexes with Schiff-Base Ligands: Syntheses, Characterization, and Catalytic Activities for the Reduction of Nitroarenes
摘要:
A series of ruthenium(II) p-cymene complexes containing Schiff-base ligands [Ru(p-cymene)LCl] [HL = pyridyl-salicylimine (2a-2d); HL = thiazol-salicylimine (2e-2h); HL = benzothiazol-salicylimine (2i-2I] have been synthesized and characterized. All Schiff-base ligands and half-sandwich ruthenium complexes were fully characterized by H-1 and C-13 NMR spectra, mass spectrometry, and infrared spectrometry. The molecular structures of ruthenium complexes 2b and 2k were further confirmed by single-crystal X-ray diffraction methods. Furthermore, these half-sandwich ruthenium complexes are active catalysts for the mild hydrogenation of nitroarenes to aromatic anilines in the presence of sodium tetrahydroborate reducing agent in water. The most efficient catalyst, 2b, was found be compatible with nitroarenes of various functional groups.
Enantioselective Aza-Henry Reaction of Imines Bearing a Benzothiazole Moiety Catalyzed by a<i>Cinchona</i>-Based Squaramide
作者:Hai-Xiao He、Wen Yang、Da-Ming Du
DOI:10.1002/adsc.201200957
日期:2013.4.15
efficient enantioselective aza‐Henry reaction of nitroalkanes to imines bearing a benzothiazole moiety catalyzed by a Cinchona‐based squaramide has been developed. In the reaction of imines, the corresponding products were obtained in good to excellent yields (up to 99%) with excellent enantioselectivities (up to >99% ee) for most of the aromatic substituted imines. The imines with electron‐withdrawing groups