Chemoselektive mono- und disilyletherbildung aus tertiären und sekundären silanen

Abstract

Tertiary and secondary silanes are O-selective. With alcohols the corresponding silyl ethers are formed. Cesium fluoride/imidazole (CsF/Im) is a better activating system than CsF alone. Primary OH groups are silylated remarkably faster under CsF/Im activation than secondary OH groups. Tertiary alcohols do not react. Primary OH groups are selectively protected also in the presence of secondary OH groups by silanes with bulky ligands such as triisopropylsilane ((i-Pr) 3SiH ( 4)). Ketones are neither reduced to silyl ethers nor transformed to silylenol ethers under the conditions employed. Secondary silanes form monosilyl ethers by amine activation; with CsF the formation of disilyl ethers predominates. A specific synthetic route to compounds with ▪ and ▪ structures is reported.