Utilization of Bis(trimethylsilyl)fluorenes as Protected Fluorenes and Fluorenones. Effective Electrooxidative Conversion into Fluorenone Dimethyl Acetals

Abstract

9,9-Bis(trimethylsilyl)fluorene (1) was prepared in one-pot procedure using LDA as base. The bis-silane 1 can act as a masked fluorene because of facile conversion to fluorene with methanol containing sodium methoxide. More specifically, 1 is smoothly transformed into fluorenone dimethyl acetal by electrooxidation in methanol; various chemical oxidants fail to react with an exception of CAN which led to fluorenone. The electrolysis of 1 involves an intermediary formation of the mono-methoxylated monosilane, which undergoes more facile conversion than 1.