Synthesis and Structure of an Enantiomerically Pure C2 Symmetric Ferrocenyl Carbene

Abstract

The straightforward, high-yield synthesis and X-ray structural analysis of the air-stable planar-chiral bis(ferrocenyl)carbene 1,3-bis-{(1R)-1-[(1R)-1-(trimethylsilyl)ferrocen-2-yl]ethyl}imidazol-2-ylidene (5) is reported. Compound 5 is obtained in four steps from the amine [(1R)-1-(dimethylamino)ethyl]ferrocene (1) upon diastereoselective silylation, methylation, nucleophilic substitution by imidazole, and deprotonation. The X-ray crystal structure of the free carbene shows the typical conformational features of the 1,2-disubstituted ferrocenyl units, as found in other ferrocenyl ligands derived from 1.