that provides opticallyactive 2-substituted hexahydro-1H-pyrrolizin-3-ones in four steps from commercially available Boc (tert-but(oxy)carbonyl))-protected proline. Diastereoisomers (−)-11 and (−)-12 were assembled from the proline-derived aldehyde (−)-8 and ylide 9via a Wittig reaction and subsequent catalytichydrogenation (Scheme 3). Cleavage of the Boc protecting group under acidic conditions, followed