Acetophenone catalytic transfer hydrogenation

Scheme 18 Catalytic transfer hydrogenation and deuteration of acetophenone. ...

To specify the position and the nature of the transferred hydride, the reaction was performed with 2-propanol-dj as solvent/donor, sodium 2-propylate as base and Fe3(CO)12/PPh3/TerPy as catalyst under optimized conditions. In the transfer hydrogenation of acetophenone a mixture of two deuterated 1-phenylethanols was obtained (Scheme 4.7, 9a and 9b). The ratio between 9a and 9b (85 15) indicated a specific migration of the hydride, albeit some scrambling was detected. However, the incorporation is in agreement with the monohydride mechanism, implying the formation of metal monohydride species in the catalytic cycle. 

Dissymmetric ferrocenyldiphosphines have been synthesized from (R)-(+)-N, N -dimethylaminoethylferrocene. The diphosphines have been used as ligands in asymmetric transfer hydrogenation of acetophenone in the presence of ruthenium catalysts.297 Asymmetric transfer hydrogenation of a,/S-unsaturated aldehydes with Hantzsch dihydropyridines and a catalytic amount of MacMillan imidazolidinone salt (12) leads to the saturated carbonyl compounds in high yields and excellent chemo-and enantio-selectivities.298 ... 

Not surprisingly, these rhodium and iridium carbene complexes were tested for their catalytic behaviour in the transfer hydrogenation of benzophenone and acetophenone (M +3), the hydrosilylation of alkynes (M +1) and also the catalytic cyclisation of acetylenic carboxylic acids (M +1). Hydrogenation works better for iridium than rhodium and for aromatic than for aliphatic ketones [40,43,44]. The iridium(I) complex is the first iridium catalyst showing activity for the cyclisation of acetylenic carboxylic acids [40]. The results for the hydrosilylation reactions were very moderate. 

A method for the monoarylation of (15,25)-l,2-diaminocyclo-hexane by means of palladium-catalyzed aromatic amination has been recently described (eq 13). The resulting new ligands were tested in the catalytic asymmetric transfer hydrogenation of acetophenone. 

E., King, F. and Xiao, J. (2004) Organic Letters, 5, 3321. The asymmetric transfer hydrogenation of various acetophenones was catalyzed in water by a ruthenium complex of PEG-TsDPEN (0.1-1.0mol%) with sodium formate, and the polymeric catalyst was readily recovered via precipitation, and reused 14 times without significant loss of either catalytic activity or stereoselectivity. 

Scheme 4 Catalytic cycle for the Ru-catalyzed transfer hydrogenation of acetophenone and reduction of the Ru-catalyst by formate to form the Ru-hydride RuH...

Scheme 32 Proposed catalytic cycle for the transfer hydrogenation of acetophenone by Ir2 complex [Ir(cod)(p-NH2)]2...

Chemoselective hydrogenation of aldehydes, ketones, and imines is achieved employing catalytic amounts of an iron complex containing both an acidic and a hydridic hydrogen atom (Scheme 4-325). This iron complex was synthesized first by Kndlker et Isolated C=C double bonds, C triple bonds, C-X, -NO2, epoxide, and ester functions are tolerated under those conditions. The same iron complex also catalyzes the transfer hydrogenations of acetophenone with isopropanol. ... 

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