Design, Synthesis, and Implementation of Sodium Silylsilanolates as Silyl Transfer Reagent

There is an increasing demand for facile delivery of silyl groups onto organic bioactive molecules. One of the common methods of silylation via a transition metal-catalyzed coupling reaction employs hydrosilane, disilane, and silylborane as major silicon sources. However, labile nature of the reagents or harsh reaction conditions sometimes renders them inadequate for the purpose. Thus, a more versatile alternative source of silyl groups has been desired. We hereby report a design, synthesis, and implementation of new storable sodium silylsilanolates that can be used for the silylation of aryl halides and pseudohalides in the presence of a palladium catalyst. The new method allows a late-stage functionalization of polyfunctionalized compounds with a variety of silyl groups, such as trimethylsilyl (TMS) group. Mechanistic studies indicate that 1) a nucleophilic silanolate attacks a palladium center to afford a silylsilanolate-coordinated arylpalladium intermediate and 2) a polymeric cluster of silanolate species assists in the intramolecular migration of silyl groups, which would pro-mote an efficient transmetalation.