Methyl (2R)-(1-benzoyl-2-benzyl-1,2,3,6-tetrahydropyridin-2-yl)carboxylate 1 reacts with osmium tetroxide to give two isomeric syn diols 2a and 2b and also with Br-2 to give two isomeric anti dibromides 4a and 4b. The major dibromide 4a gave rise to the lactone 5 on standing, the crystal structure of which is reported.