Asymmetric hydrogenation of o ‐Cresol and m ‐Cresol catalyzed by silica‐supported methylcellulose–L‐alanine–Pd complex

Silica‐supported methylcellulose–L‐alanine–palladium complex (SiO 2 ‐MC–LA–Pd) has been prepared and found to be a high optically active catalyst for asymmetric hydrogenation of o ‐cresol and m ‐cresol to give ( S )‐2‐methylcyclohexanone and ( R )‐3‐methylcyclohexanone, respectively, at 25 ° C and under an atmospheric hydrogen pressure. The optical yields of ( S )‐2‐methylcyclohexanone and ( R )‐3‐methylcyclohexanone amounted to 91.5 and 68.5%, respectively, when optimum Pd content in SiO 2 ‐MC–LA–Pd complex, reaction temperature and solvent were selected. SiO 2 ‐MC–LA–Pd catalyst also has shown high stability. The optical yields for ( S )‐2‐methylcyclohexanone and ( R )‐3‐methylcyclohexanone were kept over 90 and 60%, respectively, when the catalyst was reused several times. Moreover, SiO 2 ‐MC–LA–Pd complex is an economical catalyst. The methylcellulose is an abundant natural biopolymer and the procedure for preparation of the complex is very simple. Copyright © 2001 John Wiley & Sons, Ltd.