Cylindrically chiral diphosphine

Synthesis of a cylindrically chiral diphosphine and asymmetric hydrogenation of dehydroamino acids... 

SYNTHESIS OF A CYLINDRICALLY CHIRAL DIPHOSPHINE AND ASYMMETRIC HYDROGENATION OF DEHYDRO AMINO ACIDS... 

The cylindrically chiral diphosphine neither changed, nor lost its reactivity and selectivity in hydrogenation reactions even after long exposure to air. In a 31P-NMR study, no detectable air-oxidation was observed even after a long exposure (3 weeks) to the atmosphere. The procedures for the synthesis of the chiral ligand and the asymmetric reaction described above are very simple, giving high enan-tioselectivity with many dehydroamino acids (Table 12.4). 

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