Asymmetric hydroformylation catalyzed by homogeneous and polymer-supported platinum complexes containing chiral phosphine ligands

Chiral (Diphosphonite)platinum Complexes in Asymmetric Hydroformylation

“…However, this excess causes significant product racemization, as observed problem for the early systems, leading to lower overall enantioselectivities [6]. To overcome these drawbacks, trapping agents, e.g., triethyl orthoformate (HC(OEt) 3 ) were added, to achieve in situ protection of the aldehyde and to reach high enantioselectivities of up to 96% [8] [9]. Alternatively, preformation of the Pt/Sn bimetallic catalyst species resulted in higher enantioselectivities as well as chemo-and regioselectivities [10] [11].…”

Synthesis of Pt compounds containing chiral (2S,4S) -pentane-2,4-diyl-bis(5H-dibenzo[b]phosphindole) as ligand and their use in asymmetric hydroformylation of styrene derivatives

“…High enantiomeric excesses in the branched aldehydes can be readily achieved by the use of platinum-tin [5][6][7][8] and rhodium [9][10][11] complexes of various chiral ligands. The transformation of the formed aldehyde products to the desired acids by oxidation is also a simple one-step procedure [12].…”

“…At low temperatures (20-40 °C) (S)-(+)-2-phenylpropanal predominates in up to 85% ee, while at temperatures above 100°C the R enantiomer prevails with a maximum of 28% ee. A further increase in enantioselectivity in this direction by increasing the temperature is limited by the increasing racemization rates [5,8,27]. The reversal of product configuration as a function of reaction temperature, which is also the feature of some analogous systems, can be attributed to kinetic effects [27,28].…”

Design of Chiral Catalysis and Asymmetric Autocatalysis for the Enantioselective Additions of Organozinc Reagents.

“…(8) (9) Highly enantioselective asymmetric autocatalytic reaction was achieved for the first time in the addition of i-Pr2Zn to pyrimidine-5-carbaldehydes using chiral pyrimidyl alkanols as asymmetric autocatalysts. When chiral pyrimidyl alkanol 34 with 95% ee was employed, it automultiplied without any loss of ee to afford itself (ref.…”