Selective Si-C Bond Cleavage as Synthetic Entry to a Functionalized Lithiosilane

摘要

Functionalized lithiosilanes are versatile reagents in organic and organometallic chemistry.They are used for the nucleophilic introduction of protecting groups and synthesis of silyl-substituted transition metal complexes or silicon-based polymers.Of all known functionalized lithiosilanes especially systems of type R_2(R_2N)SiLi (developed by K.Tamao) are used for these purposes.In contrast to closely related alkyllithiums,methods of preparation for lithiosilanes such as Si-Si bond cleavage of disilanes or metal-metal exchange reactions are limited to specialized starting compounds and can result in the formation of byproducts.Our interest in this field concerns an alternative and simple access to functionalized or even highly enantiomerically enriched lithiosilanes,which are generally prepared by Si-Si bond cleavage of suitable disilanes such as highly enantiomerically enriched (R)-1 (cf.Scheme 1).In comparison to disilanes,functionalized tetra-organosilanes are more readily accessible starting materials and easier to handle.