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Cubic Siloxanes with Both Si−H and Si−O t Bu Groups for Site‐Selective Siloxane Bond Formation
Author(s) -
Saito Shohei,
Yamasue Nao,
Wada Hiroaki,
Shimojima Atsushi,
Kuroda Kazuyuki
Publication year - 2016
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201601906
Subject(s) - alkoxy group , siloxane , bifunctional , silylation , catalysis , hydrolysis , chemistry , crystallography , condensation reaction , cage , materials science , medicinal chemistry , stereochemistry , organic chemistry , polymer , alkyl , mathematics , combinatorics
Cage‐type siloxanes have attracted increasing attention as building blocks for silica‐based nanomaterials as their corners can be modified with various functional groups. Cubic octasiloxanes incorporating both Si−H and Si−O t Bu groups [( t BuO) n H 8− n Si 8 O 12 ; n =1, 2 or 7] have been synthesized by the reaction of octa(hydridosilsesquioxane) (H 8 Si 8 O 12 ) and tert ‐butyl alcohol in the presence of a Et 2 NOH catalyst. The Si−H and Si−O t Bu groups are useful for site‐selective formation of Si−O−Si linkages without cage structure deterioration. The Si−H group can be selectively hydrolyzed to form a Si−OH group in the presence of Et 2 NOH, enabling the formation of the monosilanol compound ( t BuO) 7 (HO)Si 8 O 12 . The Si−OH group can be used for either intermolecular condensation to form a dimeric cage compound or silylation to introduce new reaction sites. Additionally, the alkoxy groups of ( t BuO) 7 HSi 8 O 12 can be treated with organochlorosilanes in the presence of a BiCl 3 catalyst to form Si−O−Si linkages, while the Si−H group remains intact. These results indicate that such bifunctional cage siloxanes allow for stepwise Si−O−Si bond formation to design new siloxane‐based nanomaterials.