| Abstrakt: |
In the course of an attempt to synthesize 2-acyloxycyclohexa-1,3-diene-Fe(CO)3complexes in nonracemic form, we reinvestigated the “fully diastereoselective” Fe(CO)3complexation of (S,S)-2-ketopinoyloxy-1,3-cyclohexadiene, which had been described by Yeh and co-workers (Organometallics2001, 20, 289−295). However, after cleaving off the chiral auxiliary unit, we only obtained racemic complexes, also for a related substrate. For this reason, we performed control experiments to exclude possible racemization mechanisms and confirmed the configurational integrity of the dienol-Fe(CO)3intermediates using stereochemically defined dihydrocarvone-derived complexes. We finally could show that the complexation described by Yeh actually proceeds without any detectable diastereoselectivity. At the end, the virtually inseparable diastereomers of the chiral complexation products could be distinguished by careful NMR and chiral HPLC analyses. |
