Concise asymmetric synthesis of (-)-halosaline and (2R,9aR)-(+)-2-hydroxy-quinolizidine by ruthenium-catalyzed ring-rearrangement metathesis

A ruthenium-catalyzed ring opening-ring closing metathesis reaction serves as the key step in the stereoselective synthesis of a new enantiopure 2-substituted-4.5-dehydropiperidine skeleton, a valuable intermediate for the synthesis of piperidine alkaloids (such as halosaline) and of hydroxylated quinolizidines (such as (2R,9aR)-(+)-2-hydroxy-quinolizidine). (C) 2004 Elsevier Ltd. All rights reserved.