Department of Chemistry
Chiral C1-symmetric 2,2':6',2"-terpyridine ligands: synthesis, characterization, complexation with copper(II), rhodium(III) and ruthenium(II) ions and use of the complexes in catalytic cyclopropanation of styrene
Three new optically pure C1-terpyridine ligands (L1-3) were prepared and the copper(II) complexes, of formula [Cu(L)Cl2], the rhodium(III) complexes, of formula [Rh(L)Cl3], and the ruthenium(II) complexes, of formula cis- or trans-[Ru(L)(X)Cl2] (X = DMSO or CO), were synthesized. Structures of a chiral C1-ligand, a copper complex, a rhodium complex and a ruthenium DMSO complex were analysed using X-ray crystal structure analysis. The copper, rhodium and ruthenium complexes were shown to be precursors of catalysts for cyclopropanation. Reaction of [Cu(L)Cl2], [Rh(L)Cl3] or cis- or trans-[Ru(L)(X)Cl2] with AgOTf converted the complex to catalyst, which in the case of trans-[Ru(L)(CO)Cl2] gave enantioselectivities of up to 67% ee for the cis-isomers of styrene cyclopropanes with t-butyl diazoacetate. Comparisons with C2-analog of copper, rhodium and ruthenium catalysts were made. © 2010 Elsevier Ltd. All rights reserved.
Asymmetric catalysis, Chiral terpyridine, Copper, Metal-catalyzed cyclopropanation, Rhodium, Ruthenium
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Yeung, Chi-Tung, Wing-Sze Lee, Chui-Shan Tsang, Shek-Man Yiu, Wing-Tak Wong, Wai-Yeung Wong, and Hoi-Lun Kwong. "Chiral C1-symmetric 2,2':6',2"-terpyridine ligands: synthesis, characterization, complexation with copper(II), rhodium(III) and ruthenium(II) ions and use of the complexes in catalytic cyclopropanation of styrene." Polyhedron 29.5 (2010): 1497-1507.