Diastereoselective Alkylation of (Arene)tricarbonylchromium and Ferrocene Complexes Using a Chiral, C 2 ‐Symmetrical 1,2‐Diamine as Auxiliary

The aminal of (benzaldehyde)tricarbonylchromium and en‐antiopure bipyrrolidine undergoes diastereoselective ortho ‐metallation with butyllithium. Quenching with various electrophiles, followed by hydrolysis of the aminal, affords ortho ‐substituted (benzaldehyde)tricarbonylchromium compounds with high ee (91–99 %). When quenched with Ph 2 PCl, a new chiral P,N‐bidentate ligand is obtained, which shows efficiency in Pd‐ and Cu‐catalysed reactions. The aminal of ferrocenecarbaldehyde could also be formed, but the ortho ‐deprotonation occurs with only moderate diastereoselectivity (70 %). (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)