Hydrogenation aryl ketones

Hydrogenation of unfunctionalized C=C Hydrogenation of a- or 8-functionalized C=0 Hydrogenation of aryl ketones Hydrogenation of unfunctionalized C=0 Hydrogenation of N-aryl or cyclic imines Hydrogenation of N-alkyl imines Hydrogenation of N-acyl-hydrazones Epoxidation of allylic alcohols Epoxidation of C=C... 

Catalysts prepared in situ from [Rh(norbornadiene)Cl]2, (+)-diop (30), and triethylamine, give significantly increased enantioselectivity in aryl ketone hydrogenation when benzene is used as solvent rather than methanol the optical yield in acetophenone reduction, for example, is raised from 53% to 80%. 

Synthesis and Properties. Polyquinolines are formed by the step-growth polymerization of o-aminophenyl (aryl) ketone monomers and ketone monomers with alpha hydrogens (mosdy acetophenone derivatives). Both AA—BB and AB-type polyquinolines are known as well as a number of copolymers. Polyquinolines have often been prepared by the Friedlander reaction (88), which involves either an acid- or a base-catalyzed condensation of an (9-amino aromatic aldehyde or ketone with a ketomethylene compound, producing quinoline. Surveys of monomers and their syntheses and properties have beenpubhshed (89—91). 

In addition, Peruzzini et al. developed, in 2007, iridium complexes of planar-chiral ferrocenyl phosphine-thioether ligands that were tested in the hydrogenation of simple alkyl aryl ketones.These complexes were diastereoselec-tively generated in high yields (85-90%) by addition of the corresponding... 

Scheme 8.33 Hydrogenations of alkyl aryl ketones with ferrocenyl phosphine-thioether ligands.

In another context, chiral thioimidazolidine ligands have been successfully applied to the ruthenium-catalysed asymmetric hydrogen transfer of several aryl ketones by Kim et al., furnishing the corresponding chiral alcohols with high yields and enantioselectivities of up to 77% ee (Scheme 9.12). ... 

With compounds containing C—H bonds y to the carbonyl moiety, one often observes intramolecular hydrogen abstraction, in contrast to the in-termolecular hydrogen abstraction by aryl ketones discussed earlier in this... 

Yu J-Q, Wu H-C, Ramarao C, Spencer JB, Ley SV 2003) Transfer hydrogenation using recyclable polyurea-encapsulated palladium efficient and chemoselective reduction of aryl ketones. J Chem Soc Chem Commun 678-679... 

Chan has discovered a completely atropdiasteroselective synthesis of a biaryl diphosphine by asymmetric intramolecular Ullmann coupling or Fe(m)-promoted oxidative coupling. A chiral atropisomeric biaryl bisphosphine ligand 2 was synthesized through this central-to-axial chirality transfer.38 Recently, a xylyl-biaryl bisphosphine ligand, Xyl-TetraPHEMP, was introduced by Moran, and is found to be effective for the Ru-catalyzed hydrogenation of aryl ketone.39... 

Scheme 3.11 Partial mechanistic scheme for the hydrogenation of aryl ketones to give the (S)-alcohol catalyzed by RuCI2((R)-binap)((R,R)-dpen)/KO Bu/H2 as based on the observed mechanism for RuH2((R)-binap)(NH2CMe2CMe2NH2).

Ru-diphosphine-diamine complexes developed originally by Noyori for the hydrogenation of aryl ketones are also suitable for the hydrogenation of imines. The best results are obtained for N-aryl imines where a Ru-duphos-diamine complex achieved up to 94% ee, albeit with relatively low activity and productivity (entry 3.7) (for data relating to cyclic imines, see Table 34.5). 

It is well accepted that the asymmetric reduction of simple dialkyl ketones generally proceeds with low enantioselectivity.68 Ohkuma et al.69 reported that hydrogenation of simple ketones can be achieved using Ru(II) catalysts in the presence of diamine and alcoholic KOH in 2-propanol. Promising results have been achieved in the asymmetric hydrogenation of alkyl aryl ketones with a mixture of an Ru-BINAP complex, chiral diamine, and KOH (Scheme 6-33). 

Scheme 143 Manganese-mediated pinacolization and hydrogenation of aryl ketones.

The reaction of the carbanion derived from diethyl methylphosphonate with perhalogenated aromatics may result in substitution of halide to yield perhaloaryl(hetaryl)methylphosphonates, which can be converted into tris- or bis-(perhaloaryl)methanes. Displacement of fluoride ion has been reported in the reaction of dimethoxycarbene with l-fluoro-2,4-dinitrobenzene and with hexafluorobenzene. The hydrodehalogenation of halogenated aryl ketones may be facilitated using hydrogen over a Pt/C catalyst. " ... 

Oxidation of aryl aldehydes or aryl ketones to phenols using basic hydrogen peroxide conditions. Cf. Baeyer-Villiger oxidation. 

Table 6.8 Hydrogenation of different aryl ketones over Cu/Al203 . (Reproduced from Reference [110].)...

Figure 7-11 shows a Friedel-Crafts acylation reaction. The reaction produces an aryl ketone, which is useful in synthesis because it makes it relatively easy to convert the ketone (RCOR) group to an alkyl (R) group. The procedure involves the catalytic hydrogenation of the aryl ketone, and it s particularly useful when the electrophile in a Friedel-Crafts alkylation is susceptible to rearrangement. 

---