Influence of the 4-Substituents on the Reversal of Enantioselectivity in the Asymmetric Hydroformylation of 4-Substituted Styrenes with PtCl(SnCl3)[(2S,4S)-BDPP]

Pongrácz, Péter and Papp, Tamara and Kollár, László and Kégl, Tamás (2014) Influence of the 4-Substituents on the Reversal of Enantioselectivity in the Asymmetric Hydroformylation of 4-Substituted Styrenes with PtCl(SnCl3)[(2S,4S)-BDPP]. ORGANOMETALLICS. pp. 1389-1396. ISSN 0276-7333

Text om401104g.pdf - Published Version Restricted to Repository staff only Download (1MB) | Request a copy

Abstract

The enantioselectivity of the asymmetric hydroformylation of 4-substituted styrenes in the presence of an in situ catalyst, formed from PtCl(SnCl3)[(2S,4S)-BDPP] and tin(II) chloride, was influenced by the reaction temperature. The preferred formation of theSand theRenantiomers of the branched aldehyde regioisomers (2a−g) was observed at low and high temperatures, respectively. The electron-donor or electron-acceptor properties of the para substituents of styrene show correlation with the changes in enantioselectivity, especially with the reversal temperature of the enantioselectivity. The reversibility of the formation of the Pt-branched alkyl intermediates, leading to the corresponding RandSenantiomers of 2-arylpropanals, depends on the Hammett constants. The electronic effect of para substituents was investigated by quantum chemical methods employing the simple olefin adducts [HPt(PH3)2(olefin)(SnCl3)]. Excellent linear correlation was found between the para substituent constants and the electrostatic potential at nuclei of the platinum atom. Equally good correlation has been established for the other atoms as well in the coordination sphere of Pt.

Actions (login required)

Edit Item