Introduction of (R)-(-)-1-Aminoindane
A practical asymmetric synthesis of nearly enantiomerically pure (R)-(-)-1-Aminoindane has been developed. The key step involves the diastereoselective heterogeneous metal-catalyzed reduction of the ketimine of 1-indanone with the chiral auxiliary (R)-phenylglycine amide. The selectivity of the asymmetric hydrogenation step was optimized with regard to metal catalyst, solvent and catalyst loading. The chiral auxiliary was removed by means of a novel non-reductive procedure. Thus, (R)-(-)-1-Aminoindane with an ee of 96% was prepared in 58% overall yield from (R)-phenylglycine amide in an effective three-step procedure.