Catalytic diastereoselective Pauson-Khand reaction: an efficient route to enantiopure cyclopenta[c]proline derivatives.

Cyclopenta[c]proline derivatives were synthesized in a stereocontrolled manner and in good yields via catalytic Pauson-Khand reactions. The starting materials, optically pure enyne amino acid derivatives, can be easily prepared by an alkenylboronic acid-mediated Mannich-type reaction. [reaction: see text]