Regioselective Synthesis of Benzylsilanols from Kobayashi‐Type Reagents via C(sp 3 )─H Bond Activating 1,4‐Palladium Migration

ABSTRACT Organosilanes constitute a useful class of compounds in various fields of research in modern organic chemistry. Discovery of unexplored reactivity and utility of organosilanes is therefore highly important to further enhance their values. In this context, a palladium‐catalyzed regioselective synthesis of benzylsilanols from Kobayashi‐type reagents has been developed through a mechanistically distinct approach involving 1,4‐palladium migration followed by intramolecular transmetalation instead of conventional aryne formation. The reaction can be combined with various prior transition‐metal‐catalyzed processes and the resulting benzylsilanols have been utilized as effective benzyl nucleophiles for the Hiyama–Denmark cross‐coupling reactions with aryl halides under simple conditions. The mechanistic experiments have also been carried out, showing that the 1,4‐palladium migration goes through a palladacycle intermediate via turnover‐limiting deprotonative C(sp 3 )─H bond activation.