A route for the preparation of sparteine-like diamines starting from natura
lly occurring amino acids has been explored. Starting from the amino acids
(S)-proline and (S)-phenylalanine, two novel sparteine-like diamines 2 and
3 have been prepared. The synthetic route involves Dieckmann condensation f
ollowed by a double Mannich reaction to set up the tricyclic structure with
control of the relative stereochemistry. During the Dieckmann and Mannich
reactions it was found that racemisation occurred either via retro-Michael
or retro-Mannich processes. Conditions for preventing racemisation in the D
ieckmann reaction were uncovered but it was not possible to prevent racemis
ation during the double Mannich reaction. Thus, the two novel sparteine-lik
e diamines 2 and 3 have been prepared in racemic form.