(1R,3S,4S)-(-)-7-tert-butoxycarbonyl-3-hydroxymethyl-7-azabicyclo[2.2.1]heptan-2-one

(1R,3S,4S)-(+)-7-tert-butoxycarbonyl-2-(2'-hydroxyethylidene)-3-hydroxymethyl-7-azabicyclo[2.2.1]heptane

(1S,2R,3E,4R)-(-)-(l)-menthyl 7-tert-butoxycarbonyl-3-[2'-(l)-menthyloxy-2'-oxoethylidene]-7-azabicyclo[2.2.1]heptane-2-carboxylate