Enantioselectivity hydrosilylation

Finally, the participation of the Ar,P-bidentated phosphinous amides 61-65 (Scheme 45) as chiral ligands in the catalytic enantioselective hydrosilylation of acetophenone with diphenylsilane is worth mentioning, despite low ee (2-20%) [52]. 

Highly enantioselective hydrosilylation of aliphatic and aromatic carbonyl compounds such as acetophenone, methyl phenethyl ketone 1813, or deuterobenz-aldehyde 1815 can be readily achieved with stericaUy hindered silanes such as o-tolyl2SiH2 or phenyl mesityl silane 1810 in the presence of the rhodium-ferrocene catalyst 1811 to give alcohols such as 1812, 1814, and 1816 in high chemical and optical yield [47] (Scheme 12.14). More recently, hydrosilylations of aldehydes... 

Fig. 2.11 Chiral ligand designs in Rh catalysts for the enantioselective hydrosilylation of carbonyl compounds...

In 2005, Riant et al. reported the synthesis of a new air-stable S/N-chelating zinc catalyst, depicted in Scheme 10.50, which was fully characterised by all spectroscopic methods. This complex, prepared from the corresponding ferrocene oxazoline, was applied to the enantioselective hydrosilylation of ketones in the presence of polymethylhydrosiloxane, PMHS, providing modest enan-tioselectivities (<55% ee). ... 

Enantioselective Hydrosilylation Employing Chiral Ferrocenyl Phosphine Ligands 285... 

A summary of the ligand effects of the palladium-catalyzed enantioselective hydrosilylation of styrene is given in Table 9. 

The enantioselective hydrosilylation of 2-pentylcyclopentenone is effected with PMHS and an active catalyst derived from (R.R)-ethylenebis(tetrahydro-indenyl)titanium difluoride and phenylsilane (EBTHI)Ti (Eq. 3 50).587 The use of diphenylsilane, a rhodium catalyst, and (W, / )-(. ,.S )-BuTRAP as the chiral ligand gives similar results.576 Other related approaches give greatly inferior enantioselectivies, 592 594... 

A solitary report of enantioselective hydrosilylative cyclization appears in the literature.64 Here, a variety of 1,6-enyne substrates are cyclized in good yields and enantioselectivities, using chirally modified cationic rhodium... 

Enantioselective Hydrosilylation by Chiral Pd Based Homogeneous Catalysts with First-Principles and Combined QM/MM Molecular Dynamics Simulations... 

Abstract The enantioselective hydrosilylation of styrene catalyzed by Pd° species... 

The Pd dichloro complexes 1 and 2 (Figure 2) are precatalysts for the enantioselective hydrosilylation reaction developed by Togni and co-workers... 

The enantioselective hydrosilylation catalyst system based on the chiral pre-catalyst dichloro l- (/ )-l- [(S)-2 (dipheaylphosphinoKP) ferrocenyl] ethyl -3- trimethyl- phenyl-5-1 H- pyrazole-tc/V) palladium, 1 (shown in Figure 2) exhibits a interesting inversion of selectivity with a series of para-... 

The study of the enantioselective hydrosilylation reaction was performed with a series of combined quantum mechanics/molecular mechanics (QM/MM) calculations [26, 30] within the computational scheme of ab initio (AIMD) (Car-Parrinello) [62] molecular dynamics. The AIMD approach has been described in a number of excellent reviews [63-66], AIMD as well as hybrid QM/MM-AIMD calculations [26, 47] were performed with the ab initio molecular dynamics program CPMD [67] based on a pseudopotential framework, a plane wave basis set, and periodic boundary conditions. We have recently developed an interface to the CPMD package in which the coupling with a molecular mechanics force field has been implemented [26, 68],... 

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