Preparation and Isolation of a Chiral Methandiide and Its Application as Cooperative Ligand in Bond Activation.

The activation of element-hydrogen bonds by means of metal-ligand cooperation has received increasing attention as alternative to classical activation processes, which exclusively occur at the metal center. Carbene complexes derived from methandiide precursors have been applied in this chemistry enabling the activation of a series of E-H bonds by addition reactions across the M-C bond. However, no chiral carbene complexes have been applied to realize stereoselective transformations to date. Herein, we report the isolation and structure elucidation of an enantiomerically pure dilithiomethane, which could be prepared by direct double deprotonation. The obtained dilithium salt was used for the preparation of the first chiral methandiide-derived carbene complex, which was applied in stereoselective cooperative S-H bond activation.