Abstract The synthesis of 1-(2-13 C)-cyclopropyl-4-phenyl-1, 2, 3, 6-tetrahydropyridine (8) is reported. Attempts were first made to prepare labeled cyclopropylamine via a cyclopropanation/Curtius rearrangement sequence, but the yields were too modest to be suitable for the synthesis of a labeled compound. The preparation of 8 was achieved via cyclopropanation of the N-formyl tetrahydropyridine derivative 21 using the Grignard ...