Synthesis of an αvβ3 integrin antagonist intermediate via asymmetric hydrogenation of an α,β-unsaturated ester with BoPhoz-iridium and BoPhoz-rhodium catalysts

The enantioselective synthesis of an αvβ3 integrin antagonist intermediate was approached via asymmetric hydrogenation of a β,β-disubstituted-α,β-unsaturated ester. As a result of the rapid parallel screening of a selection of ligands and catalysts, we found that neutral Me-BoPhoz-rhodium and iridium catalysts effect the required transformation with a high enantioselectivity. Both the activity and selectivity of the catalysts were strongly dependent on the choice of solvent and counter-ion. The addition of iodine modified the iridium catalyst such that the reduction of the 3-substituted quinoline ring took place.

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