Using Rh catalysts

As Table 5 indicates, alkyl aryl ketones are the best substrates for this reaction. This has also been the case for the previously developed chiral ligand systems. Nevertheless, there have been substantial improvements in enantioselectivity for the reactions of alkenyl methyl ketones and alkyl methyl ketones, using Rh-catalysts with chiral ligands 195a191, 206b207, and 207209. 

Optically active, saturated carbonyl compounds and allylic alcohols were prepared via 1,4- and 1,2-asymmetric hydrosilation of enones using Rh catalysts bearing chiral ligands. For example, 1,4-hydro-silation of a,p-unsaturated ketones afforded the corresponding optically active ketones in 1.4-15.6% ee (Scheme 63). ... 

Selective hydrogenation of one phenyl ring in polyphenyl compounds is hardly possible using Rh catalysts, however, the reduction of l-methyl-4-(2,2-diphenyl-2-hydroxyethyOpiperazine 1 as the dihydrochloride salt leads to selectively reduced 2. Rhodium catalysts are less sensitive to poisoning by nitrogen compounds than other metal catalysts when carried out on rhodium-on-alumina ... 

Table 4 Molecular Imprinting Effect in the Reduction of Acetophenone derivatives by Using Rh Catalyst...

Table 3. Molecular imprinting effect in reduction by using Rh catalyst with templated and non-templated polymers 35a and 35b.

Since the pioneering work, various C-H bond addition reactions across alkynes using Rh catalysts have been developed. Kisch and coworkers [75] reported that addition of an ortho-C- H bond of azobenzenes to diarylacetylenes occurs smoothly in the presence of RhCl(PPh3)3. Under the reaction conditions, the alkenylarenes formed undergo cyclization to produce N-aminoindole derivatives (Scheme 18.75). 

Additionally, the first NHC-Rh-catalyzed hydrosilylation/cyclization of enynes was achieved using Rh catalyst 93 by Chung and co-workers (Equation (13.6)). "... 

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