1 For example, 3-endo-alkyl analogs & with an R substituent z to the Cl-C6 bond can be transformed 2 into 2, 6-cis-dialkyl substituted piperidines 3. la, 2- We have earlier described a synthetic approach from aldimines to 3-substituted-5, 6-dehydroisoquinuclidines having predominately R= exo substitution-as in 1. 3 We here describe a highly stereoselective synthesis of the 3-endo-alkyl-5, 6-dehydroisoquinuclidine synthons a-~ and the parent & ...