TY - JOUR
T1 - Protecting and Leaving Functions of Trimethylsilyl Groups in Trimethylsilylated Silicates for the Synthesis of Alkoxysiloxane Oligomers
AU - Yoshikawa, Masashi
AU - Tamura, Yasuhiro
AU - Wakabayashi, Ryutaro
AU - Tamai, Misa
AU - Shimojima, Atsushi
AU - Kuroda, Kazuyuki
N1 - Funding Information:
We thank Dr. T. Shibue and Mr. N. Sugimura (Materials Characterization Central Lab., Waseda University) for their help with NMR and MS measurements. This work was supported in part by JSPS KAKENHI (Grant-in-Aid for Scientific Research (B), No. 15H03879).
Publisher Copyright:
© 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
PY - 2017/11/6
Y1 - 2017/11/6
N2 - 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 SiO4, RSiO3, or R2SiO2 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 BiCl3 as a catalyst. TMS groups were substituted with alkoxysilyl groups, leading to the synthesis of alkoxysiloxane oligomers. Siloxane oligomers composed of RSiO3 and R2SiO2 units were synthesized more efficiently than those composed of SiO4 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.
AB - 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 SiO4, RSiO3, or R2SiO2 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 BiCl3 as a catalyst. TMS groups were substituted with alkoxysilyl groups, leading to the synthesis of alkoxysiloxane oligomers. Siloxane oligomers composed of RSiO3 and R2SiO2 units were synthesized more efficiently than those composed of SiO4 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.
KW - Lewis acids
KW - nucleophilic substitution
KW - protecting groups
KW - siloxane oligomers
KW - trimethylsilyl groups
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U2 - 10.1002/anie.201705942
DO - 10.1002/anie.201705942
M3 - Article
C2 - 28895273
AN - SCOPUS:85032294955
SN - 1433-7851
VL - 56
SP - 13990
EP - 13994
JO - Angewandte Chemie - International Edition
JF - Angewandte Chemie - International Edition
IS - 45
ER -