Single-Atom Ligation of Four Different Alcohols at One Silicon Center: Methodology Development and Proof of Concept

While critical and indispensable in diversified areas, organosilicon compounds are not naturally occurring and all rely on chemical synthesis. The de novo synthesis of them via quadruple substitutions of tetrachlorosilane was one of the most straightforward and common practices but confronted over-substitution challenges for heteroleptic silanes, especially the ones with four different substituents. Although selective and iterative substitutions at silicon have achieved notable achievements, methods for fully heteroleptic tetraalkoxysilanes are still lacking. Herein, we established the key dephenylative etherification reaction coupling phenylsilanes and alcohols to alkoxysilanes and then developed triphenylchlorosilane (Ph₃SiCl) as the surrogate to tetrachlorosilane for the iterative and controllable ligation of four different alcohols to one silicon center as fully heteroleptic tetraalkoxysilanes. Mechanistic studies revealed the unusual transformations of Wheland intermediates into both silicon cations and silylated phenylhalonium ions in low and comparable activation barriers.