A transannular reaction has been utilized effectively for the stereospecific synthesis of the pyrrolizidine alkaloid derivative (±)-isoretronecanol. The keto ester, ethyl 1-benzyl-1-azacyclooctan-5-one-4-carboxylate, resulting from the high-dilution Dieckmann cyclization of diethyl γ,γ′-benzyliminobisbutyrate, was converted into its transannular salt, ethyl 4-benzyl-8-hydroxypyrrolizidine-1-carboxylate perchlorate. Hydrogenation of this compound using palladium-on-charcoal catalyst produced ethyl (±)-isoretronecanolate perchlorate, from which the base was liberated and reduced to (± )-isoretronecanol with lithium aluminum hydride. 1-Benzyl-1-azaeyclooctan-5-one perchlorate could be hydrogenolyzed to pyrrolizidine perchlorate, 1-benzyl-lazacyclooctan-5-one to pyrrolizidine, ethyl 1-benzyl-1-azacyclooctan-S-one-4-carboxylate to a mixture of ethyl (±)-isoretronecanolate and the corresponding Δ1,8-dehydro ester, and 1-benzyl-1-azacyclodecan-6-one to quinolizidine. The use of the transannular salt as an intermediate in the catalytic hydrogenation step is more efficient than the use of the corresponding base. © 1969, American Chemical Society. All rights reserved.