A PROTECTIVE STRATEGY IN CARBENE COMPLEX CHEMISTRY - SYNTHESIS OF FUNCTIONALIZED FISCHER CARBENE COMPLEXES VIA DIANION FORMATION

Anionic derivatives of Fischer-type carbene complexes (A and B) are stable toward strong bases and nucleophiles, and their organic moieties R and R2 can be elaborated under strongly basic conditions to provide access to heteroaromatic and aliphatic carbene complexes bearing organic functional groups. The concept of anionic protection has been illustrated by the reactions of dianions 9 and 14 and the preparation of carbene complexes possessing up to four chiral centers. Some attempts to effect ortho lithiation of aromatic carbene complexes are also described.