Synthesis of a 13 C labeled N ‐cyclopropylamine tetrahydropyridine derivative

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 reagent of ethyl bromide and Ti(O‐ i Pr) 4 as a catalyst. The synthesis proceeded in high yield (82%). The method has a wide potential for the synthesis of other cyclopropyl ring labeled and substituted cyclopropyl ring labeled tetrahydropyridine dervatives which can be used in Monoamine Oxidase (MAO) and Cyt P 450 enzymes mechanistic studies. Copyright © 2002 John Wiley & Sons, Ltd.