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Protecting and Leaving Functions of Trimethylsilyl Groups in Trimethylsilylated Silicates for the Synthesis of Alkoxysiloxane Oligomers
Author(s) -
Yoshikawa Masashi,
Tamura Yasuhiro,
Wakabayashi Ryutaro,
Tamai Misa,
Shimojima Atsushi,
Kuroda Kazuyuki
Publication year - 2017
Publication title -
angewandte chemie
Language(s) - English
Resource type - Journals
eISSN - 1521-3757
pISSN - 0044-8249
DOI - 10.1002/ange.201705942
Subject(s) - trimethylsilyl , siloxane , chemistry , alkoxy group , steric effects , polymer chemistry , leaving group , protecting group , silsesquioxane , molecule , organic chemistry , catalysis , alkyl , polymer
The concept of protecting groups and leaving groups in organic synthesis was applied to the synthesis of siloxane‐based molecules. Alkoxy‐functionalized siloxane oligomers composed of SiO 4 , RSiO 3 , or R 2 SiO 2 units were chosen as targets (R: functional groups, such as Me and Ph). Herein we describe a novel synthesis of alkoxysiloxane oligomers based on the substitution reaction of trimethylsilyl (TMS) groups with alkoxysilyl groups. Oligosiloxanes possessing TMS groups were reacted with alkoxychlorosilane in the presence of BiCl 3 as a catalyst. TMS groups were substituted with alkoxysilyl groups, leading to the synthesis of alkoxysiloxane oligomers. Siloxane oligomers composed of RSiO 3 and R 2 SiO 2 units were synthesized more efficiently than those composed of SiO 4 units, suggesting that the steric hindrance around the TMS groups of the oligosiloxanes makes a difference in the degree of substitution. This reaction uses TMS groups as both protecting and leaving groups for SiOH/SiO − groups.