Silicon-containing compounds are increasingly vital in pharmaceutical and agrochemical applications, yet existing silylation methods face critical limitations: poor reactivity of unactivated silanes and instability of activated silylation reagents and their products. Here, we present a seven-membered dialkoxysilyl unit, dioxasilepane, abbreviated as Si(pan), that combines exceptional stability with controllable reactivity. We demonstrate a versatile method for Si(pan)Me incorporation into organic molecules through reactions with diverse aryl, alkenyl, and alkyl chlorides. Notably, we have isolated and structurally characterized the key silylpotassium intermediate as its 18-crown-6 complex through X-ray crystallography. Experimental mechanistic studies reveal that this silylpotassium species mediates the transformation primarily through halogen-metal exchange (HME). Computational investigations confirm the HME pathway while suggesting a concurrent S