Generation of 2-Lithio-2-(trimethylsilyl)silacyclopentane and 2-Lithio-2-(phenylthio)silacyclopentane and Their Use for the Synthesis of 1,4-Butanediols and γ-Hydroxy Ketones

Treatment of 2-(trimethylsilyl)silacyclopentane with t-butyllithium in THF–HMPA gave 2-lithio-2-(trimethylsilyl)silacyclopentane in good yield. An addition of alkyl iodides to the lithium compound provided 2-alkyl-2-(trimethylsilyl)silacyclopentanes which were converted into 1-alkyl-1,4-butanediols upon treatment with H2O2–KF and successively with n-Bu4NF. Reaction of 2-lithio-2-(trimethylsilyl)silacyclopentane with aldehydes gave 2-alkylidenesilacyclopentanes, which were transformed into γ-hydroxy ketones by oxidative cleavage of carbon-silicon bonds. 2-Lithio-2-(phenylthio)silacyclopentane, derived from 2-(phenylthio)silacyclopentane and t-butyllithium, afforded alkenyl sulfides having silylalkyl substituent upon treatment with aldehydes. Oxidative cleavage of carbon–silicon bonds followed by hydrolysis of alkenyl sulfide moiety also provided γ-hydroxy ketones.