Hydrosilylation and Related Reactions

An enantioselective metal-free hydrosilylation of aromatic ketones (and also of their imines) employs a quinolyloxazoline (88), which brings about a relatively long-range induction.262 

A rhodium(I)-diphosphine complex which is P-chiral catalyses enantioselective hydrosilylation of a range of simple ketones.263 After acidic workup, the corresponding alcohols are obtained in high yields and ees up to 99%. 

High-valent rhenium dioxo complexes, ReC 2l(PR3)2, catalyse the hydrosilylation of carbonyl compounds.264 DFT calculations suggest rate-determining dissociative addition of the Si-H bond (of H-Si-alkyl3) across the Re=0 bond, with subsequent carbonyl coordination and reduction. 

Metal complexes of a C2-symmetric bisproline catalyse the asymmetric hydrosilylation of ketones 29Si NMR spectra provide evidence of the mechanism. 265  

Imidazolium salt (91) is an enantioselective catalyst for crossed aldehyde-ketone benzoin cyclization.267 Most examples involve 6-oxoaldehydes giving a-hydroxycyclo- hexanones, although a 5-oxo- to -cyclopentanone case is also illustrated. Considerable variation in functional group type - aromatic, aliphatic, alicyclic - is tolerated. 

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Marciniec, B. Hydrosilylation and Related Reaction of Silicon Compounds. In Applied Homogeneous Catalysis with Organometallic Compounds Cornils, B., Herrmann, W. A., Eds. VCH Weinheim, Germany, 1996 pp 487-506. 

Nishiyama H, Itoh K (2000) Asymmetric hydrosilylation and related reactions. In Ojima I (ed) Catalytic asymmetric synthesis, chap 2,2nd edn. Wiley-VCH, New York... 

This chapter will summarize the recent advances in hydrosilylation and related reactions catalyzed by transition metal complexes since this subject was reviewed in The Chemistry of Organic Silicon Compounds in 1989 that covered the advances till the end of 19863. 

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