Two types of cyclododecasiloxanes possessing Si–H and Si–OEt side groups were polymerized by the Piers-Rubinsztajn (P-R) reaction. Cyclododecasiloxane possessing both methyl and ethoxydimethylsilyl side groups (Cyclo12-Me-SiMe2(OEt)) was synthesized by ethoxylation of cyclododecasiloxane possessing both methyl and dimethylsilyl side groups (Cyclo12-Me-SiHMe2). Cyclo12-Me-SiMe2(OEt) and Cyclo12-Me-SiHMe2 were polymerized by the P-R reaction, using B(C6F5)3 as a catalyst. The original cyclic structures were retained after the reaction without cleavage of the Si–O–Si bonds. Dimethylsilane elimination between two side –SiHMe2 groups and the consecutive siloxane-bond formation occurred concomitantly during the main P-R reaction. The effectiveness of the P-R reaction between oligosiloxanes toward preparation of polyorganosiloxanes with well-defined architectures has been demonstrated.
The controlled synthesis of oligosiloxanes with well‐defined structures is important for the bottom‐up design of siloxane‐based nanomaterials. This work reports the synthesis of various polycyclic and cage siloxanes by the hydrolysis and intramolecular condensation of monocyclic tetra‐ and hexasiloxanes functionalized with various alkoxysilyl groups. An investigation of monoalkoxysilylated cyclosiloxanes revealed that intramolecular condensation occurred preferentially between adjacent alkoxysilyl groups to form new tetrasiloxane rings. The study of dialkoxy‐ and trialkoxysilylated cyclotetrasiloxanes revealed multistep intramolecular condensation reactions to form cubic octasiloxanes in relatively high yields. Unlike conventional methods starting from organosilane monomers, intramolecular condensation enables the introduction of different organic substituents in controlled arrangements. So‐called Janus cubes have been successfully obtained, that is, Ph4R4Si8O12, in which R=Me, OSiMe3, and OSiMe2Vi (Vi=vinyl). These findings will enable the creation of siloxane‐based materials with diverse functions.
Polycyclic and cage siloxanes were synthesized by hydrolysis and intramolecular condensation of monocyclic tetra‐ and hexa‐siloxanes functionalized with alkoxysilyl groups. Intramolecular condensation occurred preferentially between adjacent alkoxysilyl groups to form new tetrasiloxane rings. Unlike conventional methods starting from organosilane monomers, intramolecular condensation enables the introduction of different organic substituents with controlled arrangements like Janus‐cubes. More information can be found in the Full Paper by K. Kuroda et al. on page 2764.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.