Mechanochemical Synthesis of Silylcyclopentenes via Ball Milling

Abstract The development of innovative methods for synthesizing silylcyclopentene compounds is particularly important for enriching and improving the synthetical toolbox of organosilicon compounds. Herein, a facile approach has been developed for the synthesis of silylcyclopentenes promoted by mechanochemically generated organolithium species as silicon nucleophiles under ball milling conditions, avoiding the requirement of large amounts of bulk solvent. This operationally simple method demonstrates good functional group compatibility, which provides a great opportunity for further exploration of the synthetic applications of silylcyclopentenes. Density functional theory calculations indicated that the transient lithiosilole intermediates undergo a stepwise nucleophilic addition process, which governs this mechanic‐force‐promoted [4+1] cycloaddition reaction.