tert-butyl (1R,3S,5S)-3-formyl-8-azabicyclo[3.2.1]octane-8-carboxylate; tert-butyl (1R,3S,5S)-rel-3-formyl-8-azabicyclo[3.2.1]octane-8-carboxylate; exo-tert-Butyl 3-formyl-8-azabicyclo[3.2.1]octane-8-carboxylate;