Chiral Dirhodium(II) Carboxylates: New Insights into the Effect of Ligand Stereo-Purity on Catalyst Structure and Enantioselectivity

Abstract

Abstract:The current report contributes to the understanding of the stereoselectivity of chiral dirhodium(II) carboxylate catalysts carrying N-protected tert-leucine ligands. Investigating the possible effect of ligand stereo-purity on catalyst structure and enantioselectivity was carried out. This was justified through a new X-ray crystal structure for Rh 2 (S,S,S,R-PTTL) 4 diastereomer.

Transition Metal Catalyzed Insertion Reactions with Donor/Donor Carbenes

“…While many transition metal catalysts have been demonstrated to be effective in C−H insertion reactions, dirhodium paddlewheel complexes have been established as a privileged class of catalysts (see Figure 5). [11–16] …”

“…While many transition metal catalysts have been demonstrated to be effective in CÀHi nsertion reactions,d irhodium paddlewheel complexes have been established as ap rivileged class of catalysts (see Figure 5). [11][12][13][14][15][16] Catalytic reactions via carbene intermediates often employ diazo compounds as precursors to metal carbenes.T hese intermediates can be isolated in some cases or generated in situ;w hen exposed to ac atalyst, nitrogen gas is extruded and the metal carbene is formed. In most cases of acceptor-substituted carbenes,d iazo transfer to as tabilized anion affords the carbene precursor.F or donor-substituted carbenes,d iazo compounds are typically generated from hydrazone precursors (Figure 3).…”

Linear One-Dimensional Coordination Polymers Constructed by Dirhodium Paddlewheel and Tetracyanido-Metallate Building Blocks

“…Moreover, dirhodium units have been used to form one-dimensional coordination compounds using bridging ligands between the dimetallic cores [18][19][20][21]. The use of other metal complexes as connectors between the paddlewheel units can lead to the formation of heterometallic one-dimensional coordination polymers, whose versatile chemical and physical properties, such as temperature dependent luminescence or modulation of their electronic structures, make those polymers promising materials [22][23][24][25]. An interesting approach to obtain this kind of heterometallic one-dimensional polymers is the use of platinum complexes to form {[Rh 2 ]-[Pt 2 ]-[Pt 2 ]} n chains, in which the different dimetallic units show direct Rh-Pt metal-metal bonds [26][27][28][29].…”