Enantioselective hydrogenation of β-dehydroamino acids on a cinchonidine-modified palladium catalyst

• Heterogeneous enantioselective hydrogenation of β-dehydroamino acids was achieved.
• The enantioselectivity approached 46% for alky substituted β-dehydroamino acids.
• The β-dehydroamino acids interacted efficiently with the chiral modifier.
• This result offered a new approach to synthesize optical β-amino acids.

Enantioselective hydrogenation of (Z)-β-dehydroamino acids on a cinchonidine-modified Pd/Al2O3 catalyst was explored. Comparative studies by using (Z)-β-dehydroamino acids and esters identified that the carboxylic group in dehydroamino acids was essentially important to get enantioselectivities (33% for aryl substituted and 46% for alkyl substituted β-dehydroamino acids). This result extended the range of enantioselective hydrogenation of α,β-unsaturated carboxylic acids on chirally modified Pd catalysts and offered a new approach to synthesize optically active β-amino acids.

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