一般来说，芳环α-位的酮或醛直接还原到亚甲基并不是很容易的事，但对于某些特殊的酮而言是可以的，如芳环上带有许多富电子基团或二芳基的酮，这类氢化相对易于进行，但一般也要在醋酸中或加入酸催化剂进行反应。

反应实例

To a stirred suspension of an appropriate aldehyde or ketone (7.5 mmol) and 10% Pd/C (0.350 g) in glacial acetic acid (10 mL), the anhydrous ammonium formate (38 mmol) was added in a single portion under argon. The resulting reaction mixture was stirred at 110oC for 10-30 min. The progress of reaction was monitored by TLC and GC. After completion of the reaction, 50 mL of CHCl3 was added, and the catalyst was removed by filtration through a

celite pad and washed with CHCl3 (20 ml). The combined organic filtrate was washed with water (20 mL* 2), then with saturated sodium bicarbonate solution (20 mL* 2), and dried over anhydrous Na2SO4. The organic filtrate on evaporation, either under reduced pressure or at normal pressure, afforded the desired product, which was further purified by column chromatography over silica gel using an ethyl acetate/hexane mixture as the mobile phase.

The phenolic derivatives were obtained by direct evaporation of filtrate after removal of the catalyst.

【Tetrahedron Lett. 1988, 29(31), 3741-3744】

2,4-dimethoxyphenyl alkyl keton (0.1 mol) was dissolved in ethanol (300 mL) and was hydrogenated at NTP in the presence of conc. HCl (1 mL) and Pd/C (5 %, 2.0 g). When the absorption of hydrogen ceased, the catalyst was filtered off. The solvent was removed to give 2,4-dimethoxylphenylalkyl benzene as an oil.

【Tomas de Paulis et al， J.Med. Chem. 1985, 28, 1263-1269】

A solution of 0.01 mol of the appropriate 2-(aroyl)arylacetic acid in 35-40 mL of glacial AcOH was shaken under an initial 3 atm of H2 at 50-60 OC, using 5% Pd on charcoal (0.2 g) as catalyst. After 7 h, the reaction mixture was filtered, and the filtrate, after concentration under reduced pressure, was diluted with HzO. The crystalline precipitate was collected by filtration and dried. Purification, when required, was accomplished by crystallization from an EtOH-H20

【Giovanni Brancaccio, Angelo Larizza, Guglielmo Lettieri, J. Med. Chem. 1981,24, 998-1000】

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